Hydrogen & Energy Symposium Wildhaus, Switzerland 2010 th ... · Modelling, Fuel Cells, Metal Hydride Batteries, Functional Materials ... Here the electrochemical conversion on the

4th Hydrogen & Energy Symposium Wildhaus, Switzerland 2010

PROCEEDINGS 1

4th INTERNATIONAL SYMPOSIUM

HYDROGEN & ENERGY Hydrogen Production, Hydrogen Storage, Hydrogen Applications, Theory and Modelling, Fuel Cells, Metal Hydride Batteries, Functional Materials

The 4th symposium “Hydrogen & Energy” follows the 3rd symposium on 25. – 30. January 2009 in Braunwald with more than 80 participants. It serves as an information platform of the fundamental science and technology and the frontiers of research on hydrogen and energy. The symposium consists of invited keynote lectures reviewing the key elements of the hydrogen cycle, i.e. the hydrogen production, hydrogen storage and hydrogen combustion and fuel cells. Furthermore, contributions on the conversion of renewable energy in general and energy carriers beside and beyond hydrogen are very welcome. The world leading experts present the current research challenges and most important results in invited and contributing talks. Early stage and experienced researchers present their newest results and the open questions on posters as well as in a one slide presentation. The conference will take place in the hotel Hirschen in the beautiful small village Wildhaus on 1'100 m above see level in the Swiss mountains. The village is the middle of a resort, quiet and offers, beside the scientific program, relaxing moments as well as plenty of sport activities. The number of participants is limited to 100.

24. - 29. January 2010

Hotel Hirschen CH-9658 Wildhaus, Switzerland Tel. (+41) (71) 998 5454 Fax (+41) (71) 998 5455 email: [email protected] URL: http://www.hirschen-wildhaus.ch/


PROCEEDINGS 2


PROCEEDINGS 3

CONTENTS

Timetable

Abstracts

SUNDAY 24. 1. 2010

I01: Prof. Dr. Boulouchos Konstantinos Properties, risks and potential of hydrogen as fuel for combustion engines

MONDAY 25. 1. 2010

I02: Dr. Cho Young Whan Critical evaluation of destabilization options for high temperature metal borohydrides

O01: Dr. Friedrichs Oliver Diborane - The key to reversible hydrogen storage

O02: Mr. Kim Ji Woo Microstructure and its effects on the hydrogen sorption properties of solid state hydrogen storage materials

O03: Ms. Lindemann Inge A study of Li-Al-borohydride as a potential candidate for hydrogen storage

O04: Dr. Remhof Arndt Rotational diffusion in MBH4 (M=Li, NA, K)

O05: Dr. Gremaud Robin Time and frequency hydrogen dynamics in LiBH4 by infrared pump probe spectroscopy

O06: Mr. Garroni Sebastiano Sorption properties of NaBH4/MH2 (M = Mg, Ti) systems

O07: Mr. Domènech-Ferrer Roger Additives effect on synthesis and decomposition of magnesium borohydride

I03: Prof. Dr. Bormann Rüdiger Tailoring Borohydrides for Reversible Hydrogen Storage

O08: Dr. Filippi Matteo Light-weight sodium alanate thin films grown by reactive sputtering

O09: Dr. Fichtner Maximilian Alanates - Synthesis, Transformation Mechanism and Technical State of the Art.

O10: Dr. Mauron Philippe Borohydrides

O11: Dr. Hu Jianjiang Li-Mg-H-N Hydrogen storage systems – composition variation, sorption properties and mechanistic dtudy

O12: Dr. Boesenberg Ulrike Reaction pathways and role of additives in reactive hydride composites


PROCEEDINGS 4

O13: Dr. Bellosta von Colbe Jose System integration: From materials research to tank system

P01: Dr. Miwa Kazutoshi Structural and thermodynamical properties of double-anion complex hydride, Mg(BH4)(NH2)

P02: Dr. Walton Allan A comparative study of porous hydrogen storage materials

P03: Dr. Stowe Ashley Analysis of Thermal Decomposition of t-Butylamine Borane

P04: Dr. Shim Jae-Hyeok Destabilization reaction of LIBH4 + MH compositesenhanced by hydrogen back pressure

P05: Mr. Schiavo Benedetto Effect of nanostructuring on the hydrogen storage properties of LaNi5 systems

P06: Mr. Gorbar Michal Porosity graded ZrO2 diaphragms for alkaline electrolysis

P07: Dr. Han Sang-Sup Measurement and evaluation techniques of hydrogen storage/release amount for solid-state materials

TUESAY 26. 1. 2010

I04: Prof. Dr. Kirchheim Reiner On the hydrogen defect interaction in the framework of a defectant concept

Oxx: Prof. Dr. Orimo Shin-ichi Lithium super (fast) Ionic conductivity (Part I)

Oxx: Dr. Matsuo Motoaki Lithium super (fast) Ionic conductivity (Part II)

O14: Dr. Langhammer Christoph Indirect nanoplasmonic sensing applied to hydrogen stogage in nanoparticles and catalysis

O16: Dr. Er Süleyman Improving hydrogen storage in magnesium

O17: Dr. Milanese Chiara Cstalysis/destabilization studies on the Mg/MgH system: From lab scale to the realization of a portable prototype.

O18: Dr. Holtappels Kai Hydrogen storage in glass capillary arrays

P08: Mr. Martelli Pascal NMR studies on Li2(BH4)(NH2) AND Li4(BH4)(NH2)3

P09: Mr. Agresti Filippo Improvement of decomposition properties of LiBH4 dispersed on modified multi-walled carbon nanotubes

P10: Mr. Pendolino Flavio Hydrogen evolution from decomposition of borohydrides: The “Boron Effect”


PROCEEDINGS 5

P11: Dr. Matsuo Motoaki Litihum fast-ion conduction in LiBH4

P12: Dr. Corno Marta Thermodynamic properties of AlH3/AlF3 and MgH2/MgF2 systems as hydrogen storage materials: A computational approach

P13: Dr. Chung Moon-Sun R&D status on hydrogen production, storage, and utilization technologies in Korea

P14: Mr. Wiedenmann Daniel

Impact of multi-scale pore structure on ion conductivity of asbestos gas separation diaphragms for alkaline water electrolysis

P15: Dr. Bielmann Michael Hydrogen powered APU for mobile rail catering service: The IHPOS-E project

WEDNESDAY 27. 1. 2010

I06: Dr. Ronnebro Ewa Light-weight metal-boron-nitrogen systems for high-capacity hydrogen storage

I07: Prof. Dr. Gregory Duncan Developments in nitridic hydrogen storage materials

O19: Dr. Cakir Deniz Reaction pathways in the reactive composite Mg(NH2)2 + LiH

O20: Dr. Hu Jianjiang Catalytic effects of LiBH4 in the hydrogen sorption reaction of 2LIH-Mg(NH2)2 system

O21: Mr. Pistidda Claudio Reaction mechanisms of formation of 2NaBH4+MgH2 by hydrogenation of 2NaH+MgB2

O22: Ms. Rongeat Carine Study of the decomposition of CA[BH4]2 prepared by reactive ball milling

THURSAY 28. 1. 2010

O15: Dr. Borgschulte Andreas From microspots to hydrogen storage by vibrational spectroscopy

O23: Mr. Kato Shunsuke Roles of surface oxide layer in hydrogen desorption processes

I09: Prof Centi Gabriele Towards solar fuels by novel photoelectrocatalytic approach

O24: Dr. Laurenczy Gabor Carbon dioxide as hydrogen vector in H2 storage and delivery

O25: Prof. Dr. Berke Heinz New catalysts and processes for amine boranes as chemical hydrogen storage materials

O26: Dr. Kozlov Alexey KEMERIT – Carbon material for energy application


PROCEEDINGS 6

O27: Dr. Muller Jiri A multidisciplinary, biological approach using solar energy to capture CO2 while producing H2 and high value products

O28: Prof. Dr. Züttel Andreas From Hydrides to Synthetic fuels

I10: Prof. Dr. Akiba Etsuo Investigation of hydrogen storage alloys and their application to on board storage tank

I11: Prof. Dr. Harris Rex A metal hydride as a means of energy storage in a canal boat

O29: Dr. Vogt Ulrich Hydrogen technology for a self-sufficient accommodation unit

O31: Dr. Gil Bardají Elisa Synthesis and properties of LIBH4-Mg(BH4)2 nanocomposites

O32: Prof. Dr. Principi Giovanni Pellets of MgH2-based composites as practical material for solid state hydrogen storage

FRIDAY 29. 1. 2010

O33: Ms Utz Inga Experimental results and simulation of a lab-scale hydrogen storage tank based on NaAlH4

O34: Dr. Balog Sandor Correlation between morphology, water uptake, and proton conductivity in radiation grafted proton exchange membranes

O35: Dr. Zakaznova-Herzog Valentina XPS study of materials for membranes in alkaline electrolysis

O37: Prof. Dr. Park Noejung First-principles investigations of hydrogenation process of graphene: In the context of hydrogen storage

O38: Prof. Dr. Jhi Seung-Hoon Optimization of metal dispersion and hydrogen adsorption in doped graphitic materials for hydrogen storage

O38: Mr. Churchard Andrew A brief review of cyclam and related complexes of nickel: Hydrogenation reduction and carbon fixation

O39: Ms. Banach Ewa Al in ZIF-8: encapsulating magic


PROCEEDINGS 7

SCIENCE OF HYDROGEN & ENERGY AWARD

List of Participants

Information

Notes


PROCEEDINGS 8

Timetable


PROCEEDINGS 9


PROCEEDINGS 10

Abstracts


11

PROPERTIES, RISKS AND POTENTIAL OF HYDROGEN AS FUEL FOR COMBUSTION ENGINES

Konstantinos Boulouchos

Laboratorium für Aerothermochemie und Verbrennungssysteme, Institut für Energietechnik, ETH Zürich, CH-8092 Zürich, Switzerland The future prospects for H2 as energy carrier depend on its competitive position along the whole energy conversion chain from primary energy sources through H2-generation, its storage and finally to the conversion to useful energy. Although H2-generation (based on electrolysis or other routes) and storage will be of decisive importance in the future, the focus of this talk will be on the energy conversion part. Here the electrochemical conversion on the basis of fuel cells, with its – at least in principle – higher efficiency, serves as benchmark, against which future developments of H2-based combustion systems will compete. In terms of applications we will discuss recent research results with pure H2 or H2-containing fuels on one hand for IC engines in transportation and on the other hand for gas turbine combustion in power generation. Although requirements for combustion optimization in the two applications are different, identical important characteristics of H2 as combustion fuel are the source of significant advantages against conventional hydrocarbon fuels in both cases. On the basis of recent experimental results we will show

that in addition to the very high laminar flame speed of H2-air mixtures themselves, both thermodiffusive and hydrodynamic instabilities in high-pressure turbulent flow fields result in extraordinary high H2-turbulent flame speeds. These lead to high ignition stability and very robust flame propagation even with very lean or otherwise diluted mixtures. Therefore high conversion efficiency together with virtually zero pollutant emissions (incl. NOX) is demonstrated not only in the laboratory but also in real-world-engines. Of course important disadvantages still persist, which may limit the applicability of H2 in high power density applications. They refer mainly to self-ignition (in IC engines) and flashback (in gas turbines) due to the high reactivity of H2-air mixtures at high pressures and temperatures. Ongoing research activities do indeed focus on promising methods to overcome these potential drawbacks. The talk will conclude with a brief summary concerning factors that will affect the future competitive standing of H2 as energy carrier for engine combustion.


12

MONDAY

MORNING


13

CRITICAL EVALUATION OF DESTABILIZATION OPTIONS FOR HIGH TEMPERATURE METAL BOROHYDRIDES

Ji Youn Lee, Jae-Hag Lim, JiWoo Kim, Yoonyoung Kim, Young-Su Lee, Jae-Hyeok Shim, Young Whan Cho

Advanced Functional Materials Research Center, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130-650, Republic of Korea

There are several options to reduce the dehydrogenation temperature of these borohydrides and they include: i) alloying including cation or anion exchange, iii) size reduction, and iv) mutual destabilization reaction. Each of them has its own merits and demerits, but a practical solution would be emerged by proper combination of these options. Here, both thermodynamic and kinetic parameters which have strong influence on dehydrogenation and hydrogenation reactions of these destabilized systems will be comprehensively evaluated using DFT calculations together with some experimental observations. In addition, some plausible explanations why the predictions do not match quite well with experimental obser-vations will also be presented. Introduction

Some group I and II metal borohydrides such as LiBH4, Mg(BH4)2, and Ca(BH4)2 have quite high hydrogen storage capacity and have recently been shown to be reversible, at least partially, with or without catalytic addi-tives. However, these borohydrides are ther-modynamically too stable to be used for many applications where the required opera-

tion temperature is well below 300℃.

Destabilization options

There are several options to reduce the dehydrogenation temperature of these borohydrides and they include: i) alloying with other metals (mixed cation boro-hydrides) or halogen group elements (mixed anion borohydrides), ii) size reduction, and iii) mutual destabilization reaction. There are reports on the existence of some mixed-cation borohydrides such as LiZn2(BH4)5

1) as well as mixed-anion alanates such as Na3AlH6-xFx.

2) However, thermodynamic stability of these complicated structure and their reversibility have yet to be confirmed. The particle or grain size reduction could bring both positive and negative effects on the hydrogen sorption behaviour of metal hydrides and these include fast reaction

kinetics, possible decrease in dehydrogenation temperature with reduced reaction enthalpy as well as rather poor cycle property and thermal conductivity.3) A more complicated but probably effective

way of destabilizing high temperature borohydrides would be mixing them with other hydrides to drive the dehydrogenation reaction further down4) and this so-called “reactive hydride composite” concept might provide a practical solution for storage applications as long as both inherently slow reaction kinetics and rather poor reversibility issues are solved.

References

[1] D. Ravnsbæk, Y. Filinchuk, Y. Cerenius, H.J. Jakobsen, F. Besenbacher, J. Skibsted, and T.R. Jensen; Angew. Chem. Int. Ed. 2009, 48, 6659 –6663.

[2] H. Brinks, A. Fossdal, B. Hauback; Journal of Physical Chemistry. C, 2008, 112, 5658-5661.

[3] V. Berube, G. Radtke, M. Dresselhaus, G. Chen; Int. J. Energy Res., 2007, 31, 637–663.

[4] Y. Cho, J. Shim, B. Lee; Calphad, 2005, 30, 65-69.

Corresponding author: Young Whan Cho, email: [email protected], Tel. (+82) (2) 958 5465


DIBORANE - THE KEY TO REVERSIBLE HYDROGEN STORAGE IN BOROHYDRIDES

O. Friedrichs1, A. Remhof1, A. Borgschulte1, F. Buchter1, S.-I. Orimo2, A. Züttel1 1Empa Materials Science and Technology, Dept. Energy, Environment & Mobility, Sec. Hydrogen & Energy, CH-8600 Dübendorf, Switzerland 2Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai, 980-8577, Japan

We show that diborane (B2H6) plays a key role in reversible hydrogen storage in borohydrides. Therefore we identified the crucial role of diborane in the formation and decomposition mechanism of borohydrides and present a model explaining the mass transport during these processes. Based on these insights, we developed a new method for the solvent-free synthesis of borohydrides at room temperature and demonstrate its feasibility with the synthesis of the following alkali and earth alkali borohydrides: LiBH4, Mg(BH4)2 and Ca(BH4)2. This method makes possible the preparation of a wide range of different borohydrides, or even mixed borohydride systems, with tuneable sorption properties.

Introduction

The influence of diborane on the sorption kinetics of borohydrides has widely been neglected so far. Partly due to the toxicity of diborane, hydrogen emitting borohydrides have been widely studied. These borohydrides work at higher temperatures, where diborane decomposes to boron and hydrogen. In this work we demonstrate that diborane plays a key role for the sorption mechanism for all borohydrides. Based on this understanding we present a new, general and solvent-free synthesis of borohydrides at room temperature.

Experimental

The synthesis of different borohydrides is performed by milling the corresponding metal hydrides in a diborane/hydrogen atmosphere. The synthesis is monitored by the pressure decrease in the system during the reaction with diborane and the final products are characterized by XRD. LiZn2(BH4)5 is used as a diborane source, which desorbs diborane and hydrogen when heated to 100°C:

Results

Milling of metal hydrides in a diborane atmosphere leads to the formation of the corresponding borohydrides as can be seen

in Figure 1 for LiBH4, Ca(BH4)2 and Mg(BH4)2.

Fig. 1. Mechanism of the Li[BH4] formation.

The method shows a high yield for the transformation (LiBH4: 94%, Ca(BH4)2: 91%, Mg(BH4)2: 73%) which is assumed to follow the reaction:

MHx + x/2 B2H6 → M(BH4)x

(M: metal, x: valence of the metal)

References [1] Friedrichs et al; Chem-Eur. J. 15 (2009) 5531 [2] Schlesinger et al; J. Am. Chem. Soc. 75

(1953) 1 [3] Ravnsbæk et al; Angew. Chem. Int. Ed. 48

(2009) 6659

Corresponding author: Oliver Friedrichs, email: [email protected], Tel. (+41) (44) 823 4153


15

MICROSTRUCTURE AND ITS EFFECTS ON THE HYDROGEN SORPTION PROPERTIES OF SOLID STATE HYDROGEN STORAGE MATERIALS

Ji Woo Kima,b,*, Jae-Pyoung Ahnb, Oliver Friedrichsc, Ki Bum Kima, Jae-Hyeok Shimb, Arndt Remhofc, Andreas Züttelc, Young Whan Chob, Kyu Hwan Oha

aSeoul National University, Dept. Materials & Engineering, Seoul, Korea bKorea Institute of Science and Technology, Advanced Functional Materials Research Center, Seoul, Korea cEmpa Materials Science and Technology, Dept. Energy, Environment & Mobility, Sec. Hydrogen & Energy, CH-8600 Dübendorf, Switzerland

Microstructural changes of metal hydrides (MgH2) and thermodynamically destabilized complex metal hydride systems (LiBH4+MH) are investigated by electron microscopes (Focused Ion Beam, Scanning and Transmission Electron Microscopes). The strong relationship between microstructures and hydrogen sorption kinetics are discussed based on the results.

Introduction

In order to have a better understanding of the hydrogen sorption behavior of MgH2 and thermodynamically destabilized LiBH4+MHx (M = Mg, Al, Y) systems microstructures are observed by electron microscopes.

Experimental

TEM specimens are prepared by focused ion beam technique. Crystallographic information is obtained by high resolution TEM micrographs and selected area electron diffraction patterns, followed by analysis with the software package. Chemical composition of the sample is obtained using electron energy dispersive spectroscopy and electron energy loss spectroscopy.

Results

Hydrogen sorption properties such as reversibility, decomposition temperatures and sorption kinetics are significantly governed by the crystallite size, distribution of catalysts and induced defects by high energy ball milling. Possible model for the hydrogen

sorption behavior and roles of catalytic additives are proposed.

Fig. 1. Formation of free Boron phase during H2

cycling of 2LiBH4+Al system

References [1] O.Friedrichs et al; Phys. Chem. Chem. Phys.

11 (2009) 1515. [2] J.W. Kim et al; J. Power Sourc. 178 (2008)

373. [3] J.W. Kim et al; Scripta Mater. 60 (2009) 1089.

Corresponding author: Ji Woo Kim, email: [email protected], Tel. (+82) (2) 880 8306


16

A STUDY OF LITHIUM-ALUMINUM-BOROHYDRIDE

I. Lindemanna, R. Domènech Ferrera, Y. Filinchukb, R. Cernyc, H.Hagemannc, L. Schultza, O. Gutfleischa aIFW Dresden,P.O. Box 270016, D-01171 Dresden, Germany bSwiss-Norwegian Beam Lines at ESRF, BP-220, 38043 Grenoble, France cCrystallography and Department of Physical Chemistry, University of Geneva, 1211 Geneva, Switzerland

The double-cation borohydride Li-Al-borohydride was successfully synthesised by high energy ball milling of AlCl3 and LiBH4. The crystal structure was obtained from high-resolution synchrotron powder diffraction data which reveals a primitive cubic cell of this very complex structure. The compound shows a very low decomposition temperature (~ 70°C) combined with an high gravimetric hydrogen density of 17.2 wt.%.

Introduction

Recently double-cation systems have attracted great interest. It was found that the desorption temperature of the borohydrides decreases with increasing electronegativity of the cation [1]. Therefore the decomposition temperature of the compound is adjustable by combining appropriate cations. Li-Al-borohydride was found to show desorption at a temperature suitable for applications (e.g. PEM fuel cell). In this work the structure of Li-Al-Borohydride is presented as well as the thermal characterisation of the compound in respect to decomposition pathway of the compound.

Experimental

AlCl3 and LiBH4 were milled in Ar with different molar ratios in order to synthesise Li-Al-Borohydride by a metathesis reaction. High resolution synchrotron radiation powder diffraction data was collected at ESFR (Grenoble) and used for structure determination. TG, DSC, in-situ Raman and thermal desorption measurements were carried out to study its decomposition behaviour.

Results

We could demonstrate the successful milling of Li-Al-Borohydride. The complex structure

shows a primitive cubic cell. Decomposition of the compound was found at a very low temperature of about 70°C. In-situ Raman measurements show the formation of LiBH4 during decomposition (see Fig.1). The high observed mass loss of about 20% points to the release of not only hydrogen but also diborane. This is the main drawback for applications because it hinders reversibility.

Fig. 1. In-situ Raman measurement in Ar at RT.

References

[1] Nakamori et al., J. Phys. Chem. Solids 69 (2008) 2292–2296

Corresponding author: Inge Lindemann [email protected], Tel. (+49) (351) 465966


17

ROTATIONAL DIFFUSION IN MBH4 (M = Li, NA, K)

Arndt Remhof#, Zbigniev Lodziana#, Pascal Martelli#, Oliver Friedrichs#, Jan Peter Embs+, Thierry Strässle+, Andreas Züttel#

+ Laboratory for Neutron Scattering, ETH Zürich & Paul Scherrer Institute, CH-5232 Villigen, Switzerland

#Empa Materials Science and Technology, Dept. Energy, Environment & Mobility, Sec. Hydrogen & Energy, CH-8600 Dübendorf, Switzerland

We present a combined experimental and theoretical study on the rotational diffusion of (BH4)- ions in

alkaline tertrahydroborides MBH4, M=(Li, Na, K). The motions are thermally activated and characterized by an activation energies in the order of 0.1 eV, typical frequencies are in the 1012Hz range. In the cubic NaBH4 and KBH4 phases the motion of the (BH4)

- ion is dominated by 90° reorientations around the fourfold symmetry axis of the cubic crystal, while it displays a three-fold jump behaviour in the low temperature phase of LiBH4. The experimental results are discussed on the basis of DFT calculations, revealing the potential energy landscape of a (BH4)

- subunit in the crystalline matrix and relating the hydrogen dynamics to the structural properties of the respective compounds.

Introduction

The four hydrogen atoms surrounding the central atom in the (BH4)

- ion form a regular tetrahedron. At ambient temperatures, the tetrahedra are not fixed in space. They perform thermally activated jumps about specific axes. Thereby the crystal structure, i.e. the electrostatic interaction, determines the rotational axis and the frequency of the rotational jumps.

Experimental

The measurements were carried out using the time-of-flight neutron spectrometer FOCUS located at the continuous spallation source SINQ at the Paul Scherrer Institute in Villigen, Switzerland.

Results

The dwell times of the rotational motion of the BH4 subunits in MBH4 are in the ps-range and vary with temperature as displayed in fig.1. The data can be fitted to the Arrhenius equation, yielding activation energies about 0.1meV. The rotational axes were determined by modelling the elastic incoherent structure factor. Within the cubic phases of NaBH4 and KBH4, 90°

reorientations dominate, while 120° rotational jumps about the c3 axes are observed for the low temperature phase of LiBH4. The different behaviours will be discussed on the basis of DFT calculations, revealing the electron distribution and the electrostatic potential energy landscape of a BH4 tetrahedron in the crystalline matrix. [1,2]

0.0015 0.0020 0.0025 0.0030 0.0035 0.00400.1

1

10

LiBH4 (LT)

LiBH4 (HT)

NaBH4

KBH4

(p

s)

1/T (K-1) Figure 1:Arrhenius behaviour of the rotational motion of the BH4 – units in alkaline borohydrides.

References [1] Remhof et al.; JPCC, 113 16834 (2009). [2] Buchter et al., PRB 78, 094302 (2008).

Corresponding author: Arndt Remhof, email: [email protected], Tel. (+41) (44) 823 4369


18

TIME AND FREQUENCY HYDROGEN DYNAMICS IN LiBH4 BY INFRARED PUMP-PROBE SPECTROSCOPY Robin Gremaud,1 Esben Ravn Andresen,2 Andreas Borgschulte,1 Peter Hamm2 and Andreas Züttel1 1Empa, Lab. Hydrogen & Energy, CH-8600 Dübendorf, Switzerland 2 Physikalisch-Chemisches Institut, Universität Zürich, Switzerland

We study deuterated LiBH4, focusing on the B-H (B-D) stretching vibrations, by infrared (IR) and IR-pump-probe spectroscopy. We report on anharmonicity and vibrational lifetimes of the B-H and B-D vibrations, as well as on the BH4 orientational relaxation by polarization-dependent IR-pump-probe measurements. We then discuss the potential of further development in pump-probe spectroscopy to study structural changes in real time in complex hydrides.

Introduction

Despite considerable research effort, the conditions for hydrogen uptake and release by LiBH4 remain harsh.[1] Fundamental studies of the BH bond yield valuable understanding to relate the microscopic to macroscopic parameters. Such studies were hitherto done by NMR and vibrational (Raman, IR, inelastic) spectroscopy. Method

2D-IR spectroscopy, which measures signal against two frequency axes (IR-pump and IR-probe), directly provides information on anharmonicity, Fermi resonances, vibrational lifetimes, spectral diffusion, and energy exchange that is not accessible by conventional vibrational approaches.[2]

Results

We study the stretching vibrations in the various BH4-nDn isotopomers (n=0…4) of partially deuterated LIBH4 by 2D-IR. The detailed understanding of the BH (BD) stretching modes provided by Raman[3], infrared spectroscopy[4] and density

functional theory calculation[3,4] allows us to isolated any particular isotopomer. We find a universal 1.5 ps vibrational lifetime, independently of the isotopomer type. The anharmonicity, nonetheless, increases with localization of the BD vibration i.e. with the decrease of the number of BD bonds per BH4-nDn. Furthermore, polarization-dependent measurements make it possible to follow in real time the orientational relaxation of the tetrahedral units in the compound. The BH2D2 tetrahedral unit remains static for up to 5 ps after pump-excitation, confirming the slow rotational relaxation and thermal disorder of the BH4 unit in the low-temperature phase.[5] We plan extend our measurements to the high-temperature phase, where reorientations and thermal effects play a major role.

References [1] O. Friedrichs et al. Chem. Eur. J. 15, 5531

(2009) [2] P. Hamm et al. Phys. Chem. B 102, 6123

(1998). [3] R. Gremaud et al. Phys. Rev. B 80, 100301(R)

(2009). [4] E. R. Andresen et al., J. Phys. Chem A 113,

12838 (2009) [5] R. Gremaud et al., MRS Fall Meeting

proceeding (2009)

Corresponding author: R. Gremaud, email: [email protected], Tel. (+41) (44) 823 4933


19

SORPTION PROPERTIES OF NaBH4/MH2 (M = Mg, TI) SYSTEMS S. Garroni1,*, C. Milanese2, A. Marini2, A. Girella2, G. Mulas3, E. Menéndez4, M. Dornheim5, C. Pistidda5, S. Suriñach1, M.D. Baró1

1Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain,2C.S.G.I., Dipartimento di Chimica Fisica "M. Rolla", Università di Pavia, Viale Taramelli 16, 27100 Pavia, Italy,3Dipartimento di Chimica, Università di Sassari, I-07100 Sassari, Italy, 4Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, D-01314 Dresden, Germany, 5Institute of Materials Research, GKSS Research Centre Geesthacht GmbH, D-21502 Geesthacht, Germany

The sorption properties of NaBH4/MH2 (M = Mg, Ti) systems prepared by high-energy ball milling have been thoroughly investigated. Concerning the system containing MgH2, the molar compositions 2:1 and 1:2 have been studied and show a multi-step pathway during desorption, where the formation of MgB2 confirms the destabilization of NaBH4 induced by the presence of MgH2. A noticeable kinetic enhancement is achieved for the system rich in MgH2 (composition 1:2). Even though, full re-absorption is obtained for neither of the two compositions, fast kinetics is achieved. The unsuspected formation of the perovskite type-hydrides NaMgH3 is detected and it is shown that this ternary phase contributes to reducing the gravimetric capacity of the systems. Conversely, in the system 2NaBH4/TiH2, there is no formation of the intermetallic TiB2.

Introduction

In this work, a detailed study of the 2NaBH4 + MgH2 and NaBH4 + 2MgH2 composites is reported. It will be demonstrated the complete desorption for both the systems and fast re-absorption kinetics. The formation of NaMgH3 is also observed. In a second part of this work the kinetic properties of the system 2NaBH4 + TiH2 are also discussed.

Experimental

Three different mixtures were prepared, namely 2NaBH4 + MgH2, NaBH4 + 2MgH2 and 2NaBH4 + TiH2. The samples were characterized by Scanning Electron Microscopy, X-ray powder diffraction, Sievert type apparatus, solid-state Nuclear Magnetic Resonance and High Pressure Differential Scanning Calorimeter (HP-DSC).

Results

Regarding the system based on MgH2, that the desorption kinetics can be improved by simply operating on the stoichiometric compound [Fig. 1]. In fact, while the system NaBH4 + 2MgH2 desorbs in 3 hours, the composite 2NaBH4 + MgH2 desorbs in 20 h indicating that the destabilization of NaBH4 is mainly correlated

with the amount of MgH2. Full absorption is not achieved for both compositions and the absorbed hydrogen is directly linked to the amount of formed NaBH4 after the process. Outstandingly, fast absorption are obtained for 2:1 and 1:2 composites. Moreover, the unsuspected formation of the perovskite type-hydride NaMgH3 is detected in the final products, which contributes to the decrease of the sorption capacity of the whole system. Remarkably, a novel route to produce this ternary hydride from Na/NaH and MgB2 is established. Concerning the 2NaBH4 + TiH2 system, the desorption is not fully reached due to the stability of the TiH2 counterpart. In contrast with the systems based on MgH2, the formation of TiB2 is not detected.

Fig. 1. Thermal programmed desorption (TPD) profile acquired on the 2NaBH4 + MgH2 (blue line) and NaBH4 + 2MgH2 (green line) systems.

Sebastiano Garroni, email: [email protected], Tel. (+34) (666) 310427

0 200 400 600 800 1000 1200-10

-8

-6

-4

-2

0

250

300

350

400

450

500

Te

mp

era

ture 2 NaBH4 + MgH2

NaBH4 + 2MgH2

wt%

H2

Time, min.


20

ADDITIVES EFFECT ON SYNTHESIS AND DECOMPOSITION OF MAGNESIUM BOROHYDRIDE.

R. Domènech-Ferrer, I. Lindeman, I. Llamas-Jansa, O. Gutfleisch.

IFW Leibnitz Institute, Dept. 21, IMW, Dresden, Germany.

The synthesis of Mg(BH4)2 has been performed by the metathesis reaction 2LiBH4+MgCl22LiCl+Mg(BH4)2 with and without 1% molar ratio of TiCl3, TiF3 and ScCl3. The synthesis of magnesium borohydride was compared by using these three additives as well as its decomposition steps. The addition of these compounds has been found to reduce the reaction yield of Mg(BH4)2 in all cases except for ScCl3. No significant improvement in the decomposition temperature was achieved in any case. However, LiCl produced in the metathesis reaction has been found to destabilize the borohydride.

Introduction

Magnesium borohydride is a very promising compound for on board hydrogen storage due to its high gravimetric concentration (14.9%wt) and the low decomposition enthalpy of 37kJ/mol H2 [1]. However, it decomposes at too high temperature. Also, the reversibility has been achieved only under very high pressures (950 bar H2 at 400°C) [2].

Experimental

LiBH4 and MgCl2 with a molar ratio 2:1 have been milled for 12 hours in 10 bar of H2 with and without 1%mol of TiCl3, TiF3 and ScCl3. Pressure and temperature were measured during milling to follow in-situ the evolution of the compounds inside the milling vial. Raman, XRD, DSC and TG measurements were performed to characterize the formation and decomposition of magnesium borohydride with and without additives.

Results

Addition of TiF3 reduces the reaction yield of magnesium borohydride due to the formation of Li2MgCl4. TiCl3 destabilizes LiBH4 by the formation and decomposition of Ti(BH4)3 during milling [3]. Only sample with ScCl3 showed a reaction yield similar than in the

case without any additive. There was no significant improvement in the decomposition temperature with any additive. However, the presence of LiCl produced during milling destabilizes Mg(BH4)2 by the formation of Li2MgCl4 at about 150°C (Fig. 1)

Figure 1: TG measurement of Mg(BH4)2 + 2LiCl in Ar atmosphere and its decomposition steps.

References [1] H. W. Li et al, Nanotechnology 20 (2009)

204013 [2] G. Severa, Gordon’s Conference (2009). [3] M. Au et al, J. Phys. Chem. C (2008), 112,

18661.

This work has been performed with the financial support of Funchy project.


21

MONDAY

AFTERNOON

FuncHy


22

TAILORING BOROHYDRIDES FOR REVERSIBLE HYDROGEN STORAGE Ulrike Bösenberg, Gagik Barkhordarian, Martin Dornheim, Rüdiger Bormann

Institute of Materials Research, GKSS Research Centre, Geesthacht, Germany

Due to the outstanding gravimetric hydrogen content, borohydrides have a high potential to be utilised as materials for hydrogen storage. However, reversible adsorption and desorption of hydrogen at reasonable temperatures and hydrogen pressures could not be achieved for single-phase borohydrides so far. A breakthrough was achieved by the development of the Reactive Hydride Composites (RHC), which contain metal borides. Thereby the sorption kinetics could be substantially improved and the reaction enthalpy could be decreased to values of technological interest. The talk will summarise the recent comprehensive understanding of the sorption kinetics and will propose critical issues for further research.

Introduction

The limited resources as well as the high emission of greenhouse gases and pollutants during the combustion of fossil fuels are serious concerns and require the development of alternative energy carriers, such as hydrogen. One of the major challenges for the implementation of hydrogen technology is its safe and reliable storage. Many metals react exothermically with hydrogen to form a hydride, the release of hydrogen requires a supply of heat and can thus be controlled. However, at present, no single metal hydride fulfils all the requirements on storage capacity, sorption temperature and reaction enthalpy. A breakthrough was achieved by the development of the Reactive Hydride Composites (RHC) [1, 2, 3].

Results

With respect to gravimetric storage capacity, the reversible system of 2LiBH4+MgH2 ↔ 2LiH+MgB2+4H2 is most favourable, as it can store up it 11.4 wt %. The reaction enthalpy amounts to -46 kJ/mol H2, which leads to an estimated equilibrium temperature at 1 bar

hydrogen of 170°C. However, kinetic constraints limit the utilisation of the composite. Therefore, transition-metal based additives were employed to enhance nucleation, growth and transformation of the MgB2 phase, which are the rate limiting factors during desorption and absorption process. The underlying mechanism has been investigated in detail and is based on the formation of nanoscale transition metal borides. As a result, transition-based additives improve the kinetics of the sorption reactions significantly [4, 5, 6].

References [1] G. Barkhordarian et al.: GKSS patent

application 2004, J. Alloys & Compounds 440 (2007) L18-L21

[2] J.J. Vajo et al.: patent application 2004, J. Phys. Chem. B 109 (2005) 3719-3722

[3] M. Dornheim et al., Scripta Materialia 56 (2007) 841-846

[4] U. Bösenberg et al., Acta Materialia, 55 (2007) 3951-3958

[5] U. Bösenberg et al., Nanotechnology, 20 (2009) 204003

[6] U. Bösenberg et al., submitted to Acta Materialia (2009)

Corresponding author: Rüdiger Bormann, email: [email protected], Tel. (+49) (921) 555200


23

LIGHT-WEIGHT SODIUM ALANATE THIN FILMS GROWN BY REACTIVE SPUTTERING Matteo Filippi1, Jan H. Rector1, Robin Gremaud1, Michiel J. Van Setten2, Bernard Dam3

1Department of Physics and Astronomy, Condensed Matter Physics, Vrije Universiteit, De Boelelaan 1081,1081 HV Amsterdam, The Netherlands2

2 Institut für Nanotechnologie, Forschungszentrum Karlsruhe P.O. box 3640 D-76021 Karlsruhe, Germany

3 Delft University of Technology, DelftChemTech, MECS, Julianaweg 136, 2628 BL Delft, The Netherlands

We report the preparation of sodium alanate (NaAlH4), a promising hydrogen storage material, in a thin film form using co-sputtering in a reactive atmosphere of atomic hydrogen. We study the phase formation and distribution, and the hydrogen desorption, with a combination of optical and infrared transmission spectroscopy. We identify the formation of sodium alanate with metallic impurities. The as-deposited NaAlH4 decomposes into NaH and Al upon high-temperature annealing. Moreover, we explore the effect of metallic titanium doping in the desorption properties of the alanate using different artificially obtained heterostructures

Introduction

Thin films are a model system to explore new metal hydride storage options, using combinatorial methods such as hydrogenography. These methods allow a fast and efficient exploration of the thermodynamic properties, having a speed of analysis that is out of reach for bulk chemical methods. Here we report for the first time the synthesis and characterization of lightweight sodium alanate thin films. Experimental

We co-sputter Na-Al thin films in a hydrogen reactive atmosphere. Atomic hydrogen is provided by a hydrogen atomic source which splits molecular hydrogen at a hot W filament. We characterize the films with a combination of optical transmission (in the UV-visible range) and infrared transmission both in the as deposited state and after high temperature annealing.

Results

We find optical signatures (in the IR and UV regions) of the formation of NaAlH4, which

decomposes into NaH and Al after desorption. The effect of metallic Ti doping is also explored. After desorption we observe for both the undoped and Ti-doped samples a macroscopic Al segregation, which probably hinders the reverse reaction under moderate conditions. This result opens the route to the analysis of the storage properties of the sodium alanate and other light-weight complex metal hydrides, such as LiAlH4, with combinatorial techniques.

References [1]R. Gremaud et al.; Advanced Materials 19

(2007) 2813 [2]M. Filippi et al.; Applied Physics Letters 95

(2009) 121904

Corresponding author: Matteo Filippi, email: [email protected], Tel. (+31) (20) 598 7912


24

ALANATES – SYNTHESIS, TRANSFORMATION MECHANISM AND TECHNICAL STATE OF THE ART

Maximilian Fichtner, Christoph Frommen, Aline Léon, Wiebke Lohstroh Alanates have been investigated for H storage applications with a focus on improving their transformation kinetics, and understanding the mechanism of the hydrogen absorption and desorption. The phase transformations in the solid, the rate limiting steps of the transformation, the evolution of different dopants during cycling and new ways to tune the thermodynamics will be discussed in more detail. Moreover, technically relevant aspects such as safety properties and coupling of alanate tanks with a high temperature PEM fuel cell will be presented.


25

BOROHYDRIDES

Ph. Mauron1, F. Buchter1, O. Friedrichs1, P. Martelli1, A. Remhof, A. Züttel1, K. Chlopek2, E.G. Bardaji2, N. Hanada, W. Lohstroh2, M. Fichtner2, R. Domènech-Ferrer 3, I.L. Jansa3, O. Gutfleisch3 1Empa Materials Science and Technology, Hydrogen & Energy, 8600 Dübendorf, Switzerland 2Karlsruhe Institute of Technology (KIT), Inst. Nanotechnology, 76021 Karlsruhe, Germany 3IFW Leibniz Institute for Solid State and Materials Research, Inst. for Metallic Materials, 01171 Dresden, Germany

The aim of the FuncHy Project from the Helmholtz-Initiative is to find a hydrogen storage material for mobile applications with a gravimetric hydrogen storage density higher than 5wt% operating at temperatures lower than 150°C with technically reasonable kinetics. Different material classes were investigated, the one presented here are the borohydrides.

Different borohydrides were successfully synthesised with different new methods. With a wet chemical method (Mg(BH4)2, Ca(BH4)2 [1]), directly from the elements (LiBH4 [2]), and by reactive ball milling (Mg(BH4)2 [3]).

Thermodynamic characterizations of the dehydrogenation reaction were made by pcT (LiBH4 [4], NaBH4, 6LiBH4+ CeH2). The reversibility of LiBH4 [4] and Mg(BH4)2 [5] has been investigated. The influence of different additives (metal chlorides) and nanoconfinement [6] on the desorption properties of Mg(BH4)2 was investigated by DSC. It has been shown that the reaction of borohydrides with metals or metal hydrides is decreasing the thermodynamic stability e.g. 2LiBH4 + Al [7] or 6LiBH4 + CeH2.

The crystal structure (β-, γ-phase of Ca(BH4)2 [8,9]) and dynamical properties (LiBH4) were successfully determined by synchrotron and neutron powder diffraction.

[1] Chlopek K, Frommen C, Leon A, et al., Synthesis and properties of magnesium tetrahydroborate, Mg(BH4)2, J Mat Chem 17

(2007) 3496 [2] Friedrichs O, Buchter F, Borgschulte A, et al., Direct synthesis of LiBH4 and LiBD4 from the elements, Acta Mater 56 (2008)

949 [3] Llamas-Jansa I, Rongeat C, Doppiu S, et al., Characterisation of complex hydrides synthesised or modified by ball

milling, Int J Mat Res 99 (2008), 553 [4] Mauron P, Buchter F, Friedrichs O, et al.O. Friedrichs, et al., Stability and reversibility of LiBH4, J Phys Chem B

112 (2008), 906 [5] Hanada N, Frommen C, Lohstroh W et al., Thermal decomposition steps of Mg(BH4)2 under He flow and H2

pressure, J Mater Chem 18 (2008) 2611 [6] Fichtner M, Zhao-Karger Z, Hu JJ, et al., The kinetic properties of Mg(BH4)2 infiltrated in activated carbon,

Nanotech 20 (2009) 204029 [7] Jin SA, Shim JH, Cho YW, et al., Reversible hydrogen storage in LiBH4-Al-LiH composite powder, Scripta Mater

58 (2008) 963 [8] Buchter F, Lodziana Z, Remhof A, et al., Structure of Ca(BD4)2 beta-phase from combined neutron and

synchrotron X-ray powder diffraction data and density functional calculations, J Phys Chem B 112 (2008) 8042 [9] Buchter F, Lodziana Z, Remhof A, et al. Structure of the Orthorhombic gamma-Phase and Phase Transitions of

Ca(BD4)2, J Phys Chem C 113 (2009) 17223


26

Li-Mg-N-H hydrogen storage systems: composition variation, Sorption properties and mechanistic study

Jianjiang Hu1, Wiebke Lohstroh1, Francesco Dolci1,2, Eveline Weidner2 and Maximilian Fichtner1 1Institute for Nanotechnology, Karlsruhe Institute of Technology, Postfach 3640, D-76021 Karlsruhe, Germany 2JRC Institute for Energy, Cleaner Energy Unit, Petten, the Netherlands

Li-Mg-N-H hydrogen storage materials offer attractive properties for solid state hydrogen storage in mobile applications. The solid state reaction is reversible at moderate conditions (i.e. at 200 °C and 100 bar H2) and the reported reaction enthalpy for the mixture Mg(NH2)2 + 2 LiH amounts to 39 kJ / mol H2 and is thus in the desired range. Starting from the above system, the hydrogen content can be increased as more LiH is added to the system. We will present a systematic study of the sorption properties of various Mg(NH2)2 + n LiH (n = 2, 3/8, 4) mixtures and the reversible hydrogen capacity, thermodynamic properties and the reaction mechanism will be presented. Remarkably, it has been shown that all mixtures exhibit an intermediate hydrogenation step where a new ternary imide phase Li2Mg2(NH)3 is formed. This intermediate phase and its implications for the actual usable hydrogen content will be discussed. In addition, the effects of various additives, i.e. LiBH4, in enhancing hydrogen desorption and absorption were investigated, which provides supportive information for the reaction mechanism.


27

REACTION PATHWAYS AND ROLE OF ADDITIVES IN REACTIVE HYDRIDE COMPOSITES Ulrike Bösenberg, Martin Dornheim, Rüdiger Bormann

Institute of Materials Research, GKSS Research Centre, D-21502 Geesthacht, Germany

In the frame of the Helmholtz initiative “Functional Materials for Mobile Hydrogen Storage” the reaction pathways as well as the role of additives in Reactive Hydride Composites (RHC) such as LiBH4-MgH2, Ca(BH4)2-MgH2 or NaBH4-MgH2 have been investigated in detail. For all systems the reaction pathway during the desorption reaction shows a strong dependency on the applied temperature and pressure. The role of transition-metal based additives and additives in general was exemplarily investigated for Zr-based additives in the LiBH4-MgH2 system. From a comprehensive analysis of the chemical state, size as well as location of the transition metal in combination with an analysis of the reaction kinetics a model is proposed, which indicates nucleation and growth of MgB2 in a limiting role during the desorption reactions under the given experimental conditions.

Introduction

The novel Reactive Hydride Composites (RHC) show extremely promising values re-garding the reaction enthalpy and capacity by weight for future mobile applications. This is achieved by an exothermic reaction to form a new compound during the endothermic de-sorption reaction. Thus, the overall reaction enthalpy is lowered. One prominent example for this material class is the system of LiBH4-MgH2 reacting to LiH and MgB2 and hydro-gen in the desorbed state. Other promising systems are Ca(BH4)2-MgH2 reacting to CaH2 and MgB2 during desorption or the system of NaBH4-MgH2. In contrast to the hampered absorption reactions of the pure boro-hydrides, the absorption reaction in the RHC was observed to be much facilitated.

Results

The reaction mechanism and probable inter-mediate phases are proposed to depend strongly on pressure and temperature during the experiment [1]. Furthermore, for the system of LiBH4-MgH2

detailed investigations were performed to analyze the function and mechanism of addi-tives [2]. Therefore, information on state, size and location the transition metal is necessary and X-ray absorption spectroscopy (XAS), anomalous small angle scattering (ASAXS)

and transmission electron microscopy (TEM) was performed exemplarily for Zr-based ad-ditives. Measurements of the as-milled as well as cycled samples indicate a chemical shift of the absorption edge of the com-pounds towards a lower oxidation state upon cycling and partly during the ball-milling process. The energy dependence of the small angle X-ray scattering near the K-absorption edge is used to access directly the resonant scattering contribution of the Zirconium based additives. The scattering curves indicate a weakly segregated network of the transition metal additives in the grain boundaries of the particles. Upon cycling a coarsening of the crystallites as well as the additives can be observed from fitting a correlation length model to the scattering curves. These observations were supported recently by TEM investigations, showing the presence of ZrB2 nanoparticles in the grain boundaries. In combination with analysis of the reaction kinetics a model is proposed, assigning nucleation and growth of MgB2 a rate limiting role during the reactions.

References [1] Bösenberg et al; in preparation [2] Bösenberg et al; Nanotechnology 20 (2009)

Corresponding author: Ulrike Bösenberg, email: [email protected], Tel. (+49) (0)4152 87 2565


28

SYSTEM INTEGRATION: FROM MATERIALS RESEARCH TO TANK SYSTEM

J. M. Bellosta von Colbe, J. Jepsen, G. Lozano, R. Bormann, M. Dornheim GKSS Research Centre Geesthacht GmbH, Institute of Materials Research, Dept. of Nanotechnology, D-21502 Geesthacht, Germany

The overall sorption behaviour of light metal hydrides is found to be critically dependent on the amount of sample and the design of the experimental vessel. As opposed to small sample batches, in large sample batches of sodium alanate, the hydrogenation kinetics are almost entirely determined by heat transfer [1], despite the fact that its reaction enthalpy is significantly lower in comparison with other well known hydrides like MgH2. Moreover, a study of the economics of hydrides shows distinct advantages in comparison with the more established storage technologies in a wide range of tank sizes [2].

Introduction

In the past most studies on light metal hydrides for hydrogen storage have been performed using small samples in the range of a few mg to several grams only. Thus, phenomena, factors and engineering aspects which reveal their influence in larger samples went unnoticed. Such are the thermal conductivity and the cost.

Concept

The advantage of solid storage systems is the fact that waste energy from the hydrogen consumer can be used during discharging of the tank and recovered during charging, redressing the energy investment of the charge and leading to an overall increase in the efficiency (Fig. 1). In order to achieve this, the size-dependent issues mentioned need to be resolved.

Results

In order to efficiently store hydrogen, the overall energy balance of the whole storage – consumer system has to be considered and optimized. Therefore, processes characterized by unrecoverable energy losses like compression and liquefaction should be minimized, and maximum use of waste energy from the surroundings should be made (Fig. 1). Thermal conduction, being the key driver for good sorption kinetics of metal hydrides, plays a fundamental role.

Heat transfer in large beds of hydrides can be improved through several methods: Using a high throughput of heating/cooling agent (which leads to high losses and has limits as to its effectiveness); modifying the design of the bed to improve heat transfer (again, a compromise has to be struck to obtain reasonable capacities, as too small beds decrease also this factor) and using high-conductivity agents to improve the intrinsic heat conductivity of the bed. This last approach, though implying slight losses in capacity, has shown to yield the best results.

Fig. 1. Operation scheme of an integrated solid storage system compared with the conventional technology.

References [1] Lozano et al, Int. J. of Hyd. Ener. 34 (2009)

1896 [2] Jepsen et al; in preparation

Corresponding author: Jose M. Bellosta von Colbe, email: [email protected], Tel. (+49) (4152) 87 2554

Energy

Storage

Hydrogen

Energy

Energy

Hydrogen

Charging

Discharging

Conventionalstorage

Solid storage

Wasteheat

Waste heat

Consumer

Storage

Energy

Consumer

Energy


29

TUESDAY


30

ON THE HYDROGEN-DEFECT INTERACTION IN THE FRAMEWORK OF A DEFACTANT CONCEPT

Reiner Kirchheim

Institut für Materialphysik, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany

For both hydrogen storage and hydrogen embrittlement the interaction of hydrogen with defects like interfaces, grain boundaries, dislocations and vacancies plays an important role. Models explaining hydrogen embrittlement as caused by enhanced local plasticity are discussed in the light of a novel concept describing solute defect interaction in a thermodynamic framework.

Introduction

In textbooks on materials science the solute/defect interaction is treated in terms of a site energy spectrum, where hydrogen atoms find sites of different energy at a defect. Fermi-Dirac Statistics is used to determine the distribution of H-atoms among these sites (a detailed analysis is provided in Ref. [1]). An alternative approach is the defactant concept, where hydrogen segregating to the defect is lowering the defect energy and, therefore, increases the rate of defect generation.

Theoretical Background

Surfactants (SURFace ACTing AgeNTS). molecules have a hydrophilic head group and a hydrophobic tail. They segregate to the water surface and lower its energy [2] Recently it has been proven that this can be applied to other crystalline defects like dislocations and vacancies as well [2] and a new term “defactants (DEFect ACTing AgeNTS)” was introduced [3], in order to cover the action of atoms segregating to defects in solids and reducing their formation energy like surfactants reduce surface energies in liquids. By using the defect

density , i.e. grain boundary area,

dislocation length, number of vacancies per volume V a unified equation for the excess solute can be defined as [3]:

BA

AA

nTV

n

V,,,

1 ,

where nA is the number of defactant atoms or molecules.

Results

The novel defactant concept is useful for a deeper insight into many phenomena like superabundant vacancies, hydrogen embrittlement, defect generation during ball milling, enhanced mobility of dislocations, thermal stability of nanocrystalline materials etc. [2].

References [1] R. Kirchheim, in: H. Ehrenreich, F. Spaepen,

(Eds.), Solid State Physics, Elsevier, Amsterdam, 2004, Vol. 59, 203-305

[2] R. Kirchheim, Acta Mater. 55 (2007) 5129-5138 and 5138-5148

[3] R. Kirchheim, Int. J. of Materials Research 100 (2009) 483

Corresponding author: Reiner Kirchheim, email: [email protected], Tel. (+49) (551) 39 5001


31

INDIRECT NANOPLASMONIC SENSING APPLIED TO HYDROGEN STORAGE IN NANOPARTICLES AND CATALYSIS

C. Langhammer, E. M. Larsson, V. P. Zhdanov, B. Kasemo and I. Zorić Chalmers University of Technology, Department of Applied Physics, 412 96 Göteborg, Sweden

Introduction

The Localized Surface Plasmon Resonance (LSPR) is a collective excitation of the free electrons in a metal nanoparticle and is highly sensitive to changes in the particle nano-environment. Nanoplasmonic sensing thus offers a combination of ultrahigh sensitivity, small sample volume and capability for real-time, remote readout as well as single-particle measurement capability. Application of LSPR-based sensing in hydrogen storage in nanoparticles and heterogeneous catalysis will be discussed.

Experimental

The “indirect nanoplasmonic sensing” technique employs arrays of Au nanodisks on a substrate as plasmonically active sensor. (Fig. 1a) The Au plasmon excitation causes a peak in the optical extinction vs. wavelength (λ) spectrum. The peak position, λmax, or width, λfwhm, measured in the experiment, is sensitive to surface changes. The Au LSPR sensor nanodisks are protected by a thin SiO2 spacer layer and decorated with smaller nanoparticles (1<D<20 nm), which are to be investigated. In the presented work indirect sensing was applied to: i) study systematically the size-dependent kinetics and thermodynamics of H2 ab/de-sorption in Pd clusters. ii) take first steps towards single nanoparticle hydrogen storage measurements. iii) detect surface coverage changes on Pt nanoparticles, with a sensitivity of less than 0.1 ML of oxygen during oxidation of H2 or CO.

Results

Hydrogen Storage: The obtained p-Δλfwhm isotherms agree very well with corresponding literature data (Fig. 1b), implying linear scaling of the Au-sensor LSPR response to hydrogen

concentration in the Pd clusters. This linear scaling is verified by complimentary QCM measurements. The obtained thermodynamic data (Sieverts and Van’t Hoff analysis) and kinetics show strong particle size effects. The scaling of the hydriding and dehydriding satisfy power and power-exponential laws in good agreement with diffusion-controlled hydriding kinetics. The latter is explained by the effect of surface tension on hydrogen desorption from the nanoparticle surface. The observed (almost) absent hysteresis for small particles is explained by complementary calculations showing that the contribution of lattice strain to the free energy of hydride formation/decomposition decreases with decreasing particle size. Catalysis: Fig. 1c shows Δλmax and the sample temperature shift, during the oxidation of H2 (H2+½ O2 H2O) over Pt nanoparticles vs. the relative H2 concentration (α = H2/(H2+O2). The most notable feature is the discontinuous step up (down) in Δλmax at αcr = 0.5, corresponding to the well known kinetic phase transition in the H2+O2 reaction, where a sudden transition occurs from an oxygen covered surface at low α to a partially hydrogen covered surface at high α. This result indicates the LSPR sensing might provide a valuable tool in the quest of bridging the pressure and materials gaps in catalysis research.

Fig. 1. a) Indirect sensing platform. b) p-Δλfwhm hydrogen ab/desortion isotherms for Pd clusters (<D>=5nm). c) Kinetic phase transition during oxidation of H2 on Pt clusters.

Corresponding author: Christoph Langhammer, email: [email protected], Tel. (+46) (0)31 772 3007


32

IMPROVING HYDROGEN STORAGE IN MAGNESIUM

Süleyman Er1, Gilles A. de Wijs2 and Geert Brocks1 1 Computational Materials Science, Faculty of Science and Technology and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands. 2 Electronic Structure of Materials, Institute for Molecules and Materials, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.

Magnesium dihydride (MgH2) will become a very useful hydrogen storage material when (de)hydrogenation kinetics are improved and desorption temperature is markedly lowered. Recent experimental and theoretical studies show that mixing MgH2 with lightweight transition metals (TM) (=Sc, Ti, V, Cr) noticeably improves the hydrogen kinetics. Here, using first-principles calculations, we show that adding Al or Si to Ti-alloyed MgH2 destabilizes it significantly. As an alternative approach, we compare thermodynamic properties of Mg-Ti-Al(Si) bulk systems to that of the nano-layered structures.

Introduction

We investigate hydrogen storage properties of some of the most promising magnesium based hydrides. In pure form, MgH2 stores 7.6 weight % hydrogen. However, for practical reasons, hydrogen kinetics of desorption and absorption have to be improved and desorption temperature (573K) has to be pulled down considerably.

Computational Methods

Density Functional Theory (DFT) calculations are performed at the level of the generalized gradient approximation (GGA) using the PW91 functional. We employ the projector augmented wave (PAW) technique and a plane wave basis set, as implemented in the Vienna Ab initio Simulation Package (VASP). The accuracy of the results is warranted using a high kinetic energy cutoff (518 eV) for the plane wave basis in combination with reasonably dense k-point meshes (at most with 0.02 Å-1 spacing).

Results

Recently, in connection with the experiments, we found that TM alloying initiates a phase transition that results in significant enhancements in the usually slow

(de)hydrogenation kinetics of bulk MgH2 [1]. Within the set of tested lightweight TMs, the most promising alloying element is identified as titanium. Here, for Mg-Ti hydrides, we establish that the same phase transition occurs both in the ordered structures, as well as in the random alloy hydrides [2]. Ti alloying alone, however, is not sufficient to decrease the stability of the hydride phases and eventually to reduce the hydrogen desorption temperature. We find that Mg-Ti hydrides are markedly destabilized by adding aluminium or silicon [3]. Contrarily, the stability of the initially immiscible Mg-Ti bulk system, the case when all the hydrogens are removed, is increased. Finally, we show that controlling the structure of Mg-Ti-Al(Si) alloys (i.e., growing them in layered forms) has a beneficial influence on the thermodynamic properties [3]. In this respect, the Mg-Ti-Al(Si) system becomes a stronger candidate for hydrogen storage.

References [1] S. Er et al., Phys. Rev. B 79, 024105 (2009). [2] S. Er et al., J. Phys.: Condens. Matter (2009). [3] S. Er et al., (in preparation)

Corresponding author: Süleyman Er, email: [email protected], Tel. (+31) (53) 489 3167


33

CATALYSIS/DESTABILIZATION STUDIES ON THE MAGNESIUM/MAGNESIUM HYDRIDE SYSTEM: FROM LAB SCALE TO THE REALIZATION OF A PORTABLE PROTOTYPE.

Chiara Milanesea, Andrea Girellaa, Giovanna Brunia, Vittorio Berbennia, Paolo Matteazzic, Amedeo Marinia

a CSGI - Physical Chemistry Dept., University of Pavia, Viale Taramelli 16, I - 27100 Pavia, Italy; b MBN Nanomaterialia SpA, Via G. Bortolan 42, I - 31050 Vascon di Carbonera (TV), Italy.

In the frame of the Italian joint project “Nanostore”, focused on Mg-based composites prepared by high energy ball milling, many solutions have been explored in order to catalyze the sorption reactions of the Mg - MgH2 system and to destabilize MgH2, lowering both its decomposition temperature and enthalpy. The best promising systems, i.e. Mg – Ni – C – TiO2 and Mg – C – MO (MO = TiO2, Nb2O5) composites, were optimized concerning stoichiometry, milling time and aggregation state (powders or pellets with different density) for the use as H2 storage media (100 g H2) in a portable 1 kW PEM-FC prototype. The first tests of the device will also be discussed.

Introduction

In this work the kinetic and thermodynamic sorption performance of Mg – Ni – C – TiO2 and Mg – C – MO (MO = TiO2, Nb2O5) composites optimized for the use as storage materials in a portable prototype is shown. The differences in the behaviour between powders and pellets (prepared with different densities by both conventional and non-conventional compaction methods) is discussed. Finally, the set-up and performance of the final version of the prototype is presented.

Experimental

The composites were prepared on industrial scale (100 g for each batch) by high energy ball milling under 5 bar Ar for different processing times (from 45 min to 240 min). Concerning lab scale analyses (500 mg samples), the activation was performed by subsequent charging/discharging runs at 350 °C and 35 bar/1 bar in a Sievert type apparatus. Subsequently, the sorption properties of the fully activated mixtures were evaluated (280°C T 350°C; 30 bar P H2 1

bar) by kinetic runs, TPD and PCI analyses. The sorption enthalpies were measured on fully activated samples (10 mg) by high pressure calorimetry. The chemical nature and the microstructure of the phases formed after milling, charging and discharging were evaluated by refinement of the experimental X-ray diffraction patterns. The performance of the best performing composites are under evaluation directly in the prototype tank (1500 g samples).

Results

Gravimetric capacities of 6.4% and 6.9% were obtained for Mg – Ni – C – TiO2 and Mg – C – MO systems respectively at T = 350 °C. At this same temperature, the lab scale analyses showed that the composites charge up to 90% of their filling up in 1.5 min maximum. Moreover, more than 98% of the full discharging, lasting 10 min, takes place with a rate fully suitable to feed the 1 kW fuel cell. The first tests of the storage materials directly in the prototype are very promising, with the storage performance being very similar to that obtained on lab scale.

Corresponding author: Chiara Milanese, e-mail: [email protected], Tel. (+39) 0382 987 670.


34

HYDROGEN STORAGE IN GLASS CAPILLARY ARRAYS

Kai Holtappels*, Martin Beckmann-Kluge*, Dan Eliezer**

* BAM Federal Institute for Materials Research and Testing, Dept. II “Chemical Safety Engineering”, Div. “Gases, Gas Plants”, 12200 Berlin, Germany

** C.En Ltd., 3 Sonnhaldenstrasse, Postfach CH-8032, Zurich, Switzerland

A new light-weight storage system is being developed. Thereby gases are stored at high pressures in glass structures which are closed by an innovative technology. Basic material tests have been carried out to determine storage capacities in dependence of main characteristics of the glasses and their structures. Stresses in the structures were modelled by FEM software to find the best structures. First storage results showed that gravimetric and volumetric storage capacities already surpassed the targets of the DoE 2010.

Introduction

Central to the realization of the profound potential of hydrogen technology is the resolution of obstacles inherent in the storage of hydrogen. Conventional storage methods pose weight, volume, safety, cost and permeation obstacles and are unable to meet future on-board application goals as defined by the US Department of Energy (DOE). The success of the hydrogen economy is entirely dependent on the meeting of these goals. A novel method of hydrogen storage which utilizes an array of thin sealed capillaries made of quartz or other glasses will be presented.

Experimental

A special set-up was installed in safety rooms in order to carry out various tests. It is possible to realize hydrogen pressures of max. 1500 bar. On the one hand systematic tests for the determination of basic material properties like burst pressures, life cycles, influences on the strength etc. have been carried out. Applying special procedure hydrogen was also stored in the glass structures.

Results

The C.En developed system ensures the safe infusion, storage, and controlled release

of hydrogen gas, under storage pressures of up to 1200 bar. These findings have been achieved in experiments conducted on individual and multiple (array) capillaries, and demonstrate the unique properties of glass materials. Thereby glasses which contains approximately a third of the density of steel whilst having three times the strength of steel led finally to light-weight systems, because significantly less material is necessary to reach the same pressure resistance. Carrying out life cycle tests it turned out that the strength is also increased by adding certain pressures to the structures ahead of the storage.

Fig. 1 Prototype for Hydrogen Storage

Corresponding author: Kai Holtappels, email: [email protected] , Tel. (+49) (30) 8104 3436


35

WEDNESDAY


36

LIGHT-WEIGHT METAL-BORON-NITROGEN SYSTEMS FOR HIGH-CAPACITY HYDROGEN STORAGE

Ewa Rönnebro

Pacific Northwest National Laboratory, 902 Battelle Blvd., Richland, WA 99354, USA

A promising high-capacity hydrogen storage material is ammonia borane, NH3BH3, releasing ca 12 wt% of hydrogen <150°C and regeneration is made feasible by a sequence of chemical reactions. We have been exploring metal hydrides and borohydrides mixed with ammonia borane, to find ways to improve sorption properties and to reduce impurity levels of borazine, diborane and ammonia. Composite materials were prepared by ball milling and characterized with respect to phase composition, chemical bonding and release rates.

Introduction

Hydrogen storage is a key technology in development of alternative energy infrastructures. The need for light-weight, high-capacity materials has shifted our focus from metal hydrides to metal borohydrides (i.e. Li, Ca, Mg). We have identified pathways for direct hydrogenation of calcium and magnesium borohydrides from their end-decomposition products at 700-900 bar H2-pressures and 300-400°C according to:

(1) 2CaH2 + CaB6 + 10H2 = 3Ca(BH4)2

(2) MgB2 + 4H2 = Mg(BH4)2 opening the door to potential high-capacity hydrogen storage applications [1,2]. Although borohydride materials can store ca 11-19 wt% hydrogen, the operation temperatures are high for practical applications and re-hydrogenation kinetics is slow. Another high-capacity material is ammonia borane, NH3BH3, releasing ca 12 wt% of hydrogen <150°C. Regeneration is made feasible by a sequence of chemical reactions. Different approaches to improve the performance have been reported in the literature, such as composite systems, scaffolding and additives [3,4,5]. By combining metal hydrides and borohydrides with ammonia borane, we are looking for ways to improve sorption properties and to

reduce impurity levels of borazine, diborane and ammonia.

Experimental

Composites of NH3BH3 and hydride materials were prepared by ball milling and characterized by in situ and ex situ analysis including XRD, Raman, NMR, DSC/TGA/MS and kinetics studies.

Results

We have studied a series of composite materials of NH3BH3 + hydrides with respect to phase composition, chemical bonding, release rates and re-hydrogenation. We will here report our experimental results comparing hydrogen sorption performance for the different composites.

References [1] E. Rönnebro et al, JPCB, 111 (42) (2007) 12045 [2] G. Severa et al, submitted (2009) [3] A. Gutowska et al, Angew. Chem. Int. Ed. 44 (2005)

3578 [4] Z. Xiong et al, Nature Materials, Vol 7 (2008) 138 [5] D.Heldebrant et al, Chem. Mater. 20 (2008) 5332

Corresponding author: Ewa Rönnebro, email: [email protected], Tel. (+1) (509) 375 6877


37

RECENT DEVELOPMENTS IN NITRIDIC HYDROGEN STORAGE MATERIALS

Duncan H. Gregory. WestCHEM, Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, UK.

Complex hydrides containing lithium and nitrogen offer new families of materials for high gravimetric capacity hydrogen uptake. Such high capacity storage is often reversible with potentially rapid sorption kinetics and good cycleability. Such nitrides, imides and amides also present vast opportunities for doping, catalysis and morphology/size control. This contirbution highlights how the materials chemistry of these hydrides can be developed from conception and discovery through to modification and optimisation. We also emphasise how an evolving understanding of storage and reaction mechanism can underpin concepts of design from a materials chemistry perspective.

Introduction

This work describes how various complementary synthesis strategies including increasing compositional complexity and nanostructuring can afford new nitridic materials for hydrogen storage. Further, we demonstrate how in- and ex-situ characterisation techniques can be harnessed to understand the mechanisms and processes of storage in these materials.

Results and Discussion

We present and discuss several different case studies from our work at Glasgow to illustrate the approaches we are taking. First, we consider the factors influencing the uptake of hydrogen in the archetypal nitride-hydrogen system, Li-N-H. Studies comparing the uptake of hydrogen by pure α-Li3N vs. commercial sources of Li3N vs. β-Li3N demonstrate certainly that sorption rate (and capacity) is mediated by purity and particle size and also possibly by crystal structure (polymorphism). The role of superionic Li+

conductivity may be instrumental in this and appears to have marked effects in the absorption and desorption of hydrogen (and lithium) in cycling between lithium imide (Li2NH) and lithium amide (LiNH2) as demonstrated by diffraction, solid state NMR and MuSR experiments. We also demonstrate that when taken to the extreme

– by chemically engineering nanostructures – tailoring particle size and morphology can dramatically improve kinetics and reversible capacity. We also consider how similar approaches might be applied to more complex nitrogen-containing systems and here we show how with the most simple 1:1 combinations in the Li-Mg-N-H system, one might both, for example, understand the mechanisms of the dehydrogenation reaction and also manipulate the rate and capacity of hydrogen uptake. We report our results from ball-milling processing, powder X-ray and neutron diffraction and temperature programmed desorption experiments.

Fig. 1. (a) Li3N nanofibres; (b) Structure of LiMgN.

References [1] D H Gregory; J. Mater. Chem. 18 (2008) 2321 [2] T. K. Mandal, D. H. Gregory; Annu. Rep. Prog.

Chem. Sect. A, 105 (2009) 21 [3] D. H. Gregory, A. G. Gordon; International

patent (2004) WO2004057070

Corresponding author: Duncan H. Gregory, email: [email protected], Tel. (+44) (0) 1413306438

(a) (b)


38

REACTION PATHWAYS IN THE REACTIVE COMPOSITE Mg(NH2)2 + LiH

Deniz Cakir1, Gilles A. de Wijs2 and Geert Brocks1

1 Computational Materials Science, Faculty of Science and Technology and MESA+ Research Institute,

University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.

2 Electronic Structure of Materials, Institute for Molecules and Materials, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands. In 2002, Chen et al [1] reported reversible hydrogen storage in a mixture of LiH + LiNH2 with a storage capacity of 6.5 wt %. However, this system requires an operating temperature in excess of 250 C to achieve a hydrogen pressure of 1 bar. Several efforts including cation substitution have been considered in order to improve the operating conditions, which is necessary for onboard applications. For instance, replacing LiH with MgH2 markedly reduces the operating temperature through the reaction MgH2 + 2LiNH2 → Li2Mg(NH)2 + 2H2 ↔ Mg(NH2)2 + 2LiH. Recent experimental results however indicate that the latter is not a simple one-step reaction and full hydrogenation of Li2Mg(NH)2 occurs in a two step sequence via an intermediate Li2Mg2(NH)3 [2,3]. In this work we examine the stability and structure of possible intermediates compounds, namely Li2-2xMgxNH, Li1-

2xMgxNH2, LixMg(NH2)2-x(NH)x, and Li2-

xMg(NH)2-x(NH2)x, by means of first-principles DFT calculations. In order to get stability of these compounds, formation enthalpies are calculated from total energy differences. We include the vibrational zero point energies in

order to get accurate results. All intermediate compounds are thermodynamically stable with respect to the elements. Next we consider possible reaction steps involving these intermediate imides/amides. We find that the intermediate amides Li1-2xMgxNH2 or mixed imide-amides LixMg(NH2)2-x(NH)x and Li2-xMg(NH)2-x(NH2)x, are energetically not favorable. In contrast, the hydrogenation reaction of Li2Mg(NH)2 via the intermediate imides Li2-2xMgxNH is energetically favorable. However, we do not find a clear preference for one specific composition, as all compounds Li2-2xMgxNH with ½ ≤ x ≤ ¾ lead to a similar reaction enthalpy. We predict that all compounds within this composition range are likely to occur as intermediates. The experimentally proposed composition, x = ⅔, lies within this range

References [1] P. Chen, Z. Xiong, J. Luo, and K. L. Tan, Nature 420, 302 (2002). [2] J. Hu, Y. Liu, G. Wu, Z. Chiong, and P. Chen, J. Phys. Chem. C 111, 18439 (2007). [3] E. Weidner, F. Dolci, J. Hu, W. Lohstroh, T. Hansen, D. J. Bull, and M. Fichtner, J. Phys. Chem. C 113, 15772 (2009).


39

CATALYTIC EFFECTS OF LiBH4 IN THE HYDROGEN SORPTION REACTION OF 2LiH-Mg(NH2)2 SYSTEM

Jianjiang Hu1, Eveline Weidner2 and Maximilian Fichtner1 1Institute for Nanotechnology, Karlsruhe Institute of Technology, Postfach 3640, D-76021 Karlsruhe, Germany 2JRC Institute for Energy, Cleaner Energy Unit, Petten, the Netherlands

LiBH4 is an effective additive in enhancing hydrogen desorption and absorption for the 2LiH-Mg(NH2)2 hydrogen storage system. We found in this study that the activation energy of the 2LiH-Mg(NH2)2 system in the dehydrogenation was lowered by approximately 14% after doping with LiBH4. By following the phase development during H2 release from the LiBH4 doped system, we observed the formation and disappearance of Li4(BH4)(NH2)3, a LiBH4 complex with LiNH2, as intermediate in the hydrogen sorption process. Phenomenally, the driving force of the faster kinetics could be originated from LiBH4 which captures and releases LiNH2, the intermediate in the pristine 2LiH-Mg(NH2)2 system, during the hydrogen sorption process. In the presence of LiBH4 the crystallization of Mg(NH2)2 took place at much lower temperatures, which might structurally favor the solid-solid hydrogen sorption reaction.

Introduction

In order to elucidate the catalytic mechanism, both kinetic analysis and phase identification were performed.

Experimental

The activation energies for both pristine and LiBH4 doped systems were measured. The crystal structure of Li4(BH4)(NH2)3 was determined with highly crystallized Li4(

11BD4)(NH2)3 by Neutron Diffraction and refined via Rietveld method. X-ray powder diffractometry and FTIR were used for the phase and composition identification in the hydrogen sorption process.

Results

The activation energies were found to be 149.9 kJ/mol for the pristine sample and 128.3 kJ/mol for the sample of 1Mg(NH2)2-2LiH-0.3LiBH4, i.e., ca. 14% reduction in the activation energy by the addition of LiBH4. XRD results reveal that Mg(NH2)2 recrystallizes at a considerably low temperature of 154°C in the presence of

LiBH4, which could be of significance for the enhancement of hydrogen desorption.

2.07 2.10 2.13 2.16 2.19 2.22 2.25 2.28-12.5

-12.0

-11.5

-11.0

-10.5

-10.0

-9.5

Ea=128.3 kJ/mol

1-2 pure 1-2-0.3

ln(

/Tm

ax

2 )

1000/Tmax

(K-1)

pristineEa = 142.9 kJ/mol

Fig. 1. Kissinger Plot of pristine and LiBH4 doped systems.

References [1] Hu, J. J.; Liu, Y.; Wu, G.; Xiong, Z.; Chua, Y.

S.; Chen, P. Chem. Mat. 2008, 20(13), 4398-4402

[2] Meisner, G. P.; Scullin, M. L.; Balogh, M. P.; Pinkerton, F. E.; Meyer, M. S. J. Phys. Chem. B 2006, 110, 4186-4192

Corresponding author: Jianjiang Hu, email: [email protected] , Tel. (+49) (7247) 82 8915


40

REACTION MECHANISMS OF FORMATION OF 2NaBH4+MgH2 BY HYDROGENATION OF 2NaH+MgB2 Claudio Pistidda1,2, Gagik Barkhordarian1, Christian Bonatto Minella1, Sebastiano Garroni3 Torben Jensen4, Yngve Cerenius5, Martin Dornheim1, Wiebke Lohstroh2, Maximiliam Fichtner2 , Rüdiger Bormann1

1 Institute of Materials Research, GKSS Research Centre Geesthacht GmbH, Max-Planck-Straße 1, D-21502 Geesthacht, Germany;

2 Institute of Nanotechnology, Forschungszentrum Karlsruhe GmbH, Postfach 3640, 76021 Karlsruhe, Germany; 3 Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain; 4 Interdisciplinary Nanoscience Centre (iNANO) and Department of Chemistry, University of Aarhus, Langelandsgabe 140, DK-8000. Denmar; 5 MAX-lab, Lund University, S-22100 Lund, Sweden

The formation mechanism of 2NaBH4+MgH2 by hydrogenation of 2NaH+MgB2 has been investigated in detail by in-situ methods. Depending on the applied hydrogen pressure several intermediate phases are observed.

Introduction

With the aim of clarifying the reaction mechanisms involved in the formation of complex borohydrides, we investigated the hydrogenation reaction of 2NaH+MgB2.

Experimental

The NaH and the MgB2 were charged into a hardened steel vial and milled for 1 hour in a Spex 8000 ball mill, with a ball to powder ratio of 10:1. In situ XRD measurements were performed at the MAX II Synchrotron, at Beam line I711 in Lund.

Results

The results presented indicate that during heating in H2 atmosphere a series of

reactions takes place. Besides the formation of NaBH4 , the formation of NaMgH3 as well as the formation of an unknown phase is observed under 50 bar H2 pressure and temperatures up to 400°C. Moreover, some of the reaction products are in the liquid state, as it is evidenced from the appearance / disappearance of the amorphous background in the SR-PXD data and the solidification peaks that appear in the DSC measurements during cooling. Hydrogenation at 5 bar H2 still yields the liquid state, however the formation of NaMgH3 as well as of the unknown phase could not be observed, consequently the formation of these two phases strongly depends on the applied hydrogen pressure.

Corresponding author: Claudio.Pistidda, email: [email protected]


41

STUDY OF THE DECOMPOSITION OF Ca[BH4]2 PREPARED BY REACTIVE BALL MILLING

Carine Rongeat1, Shunsuke Kato2, Andreas Borgschulte2, Andreas Züttel2, Ludwig Schultz1 and Oliver Gutfleisch1

1IFW Dresden, Institute for Metallic Materials, D-01069 Dresden, Germany 2Empa Materials Science and Technology, Dept. Energy, Environment & Mobility, Sec. Hydrogen & Energy, CH-8600 Dübendorf, Switzerland

Ca[BH4]2 is one of the more interesting material for solid state hydrogen storage due to its high hydrogen content and suitable thermodynamic properties for mobile application. This compound can be synthesised by reactive ball milling of a mixture of CaH2 and CaB6 under high hydrogen pressure. This technique enables to add directly a dopant to the mixture during the synthesis process to improve it. The effect of different dopant on the decomposition is discussed in details.

Introduction

The synthesis of Ca[BH4]2 from the decomposition products CaB6 and CaH2 necessitates drastic conditions at 440°C and 700 bar [1]. Reactive ball milling is used as an alternative technique near room temperature. The decomposition of this material is analysed here by a combination of different characterisation techniques.

Experimental

The starting mixtures CaH2 + CaB6 with TiCl3 or TiF3 as additives were ball milled under 140 bar H2 to mechano-synthesised Ca[BH4]2 through reaction (1).

(1) 24262 ][3102 BHCaHCaBCaH

Infrared (IR) spectroscopy was used for the characterisation of the as-milled compounds. The decomposition was studied by thermal desorption spectroscopy (TDS) in high vacuum and differential scanning calorimetry (DSC) under H2 atmosphere with maximum 500°C.

Results

After 24 h milling of CaH2 and CaB6 under 140 bar H2, we can observe a H2 pressure decrease in the vial related to H2 absorption from the mixture. The quantity of H2 absorbed represents 19% of the total amount expected for the complete reaction (1).

Despite this low yield, it is possible to identify Ca[BH4]2 by IR spectroscopy [2]. The decomposition of the Ca[BH4]2 phase formed during milling follows a multi-step process (Figure 1) which differs if it performed in vacuum or H2 atmosphere. It is suggested that different intermediate phases are formed depending on the atmosphere.

Fig. 1. TDS spectra of H2 (top) and B2H6 (bottom) releases for the decomposition of pure Ca[BH4]2 (a) and of milled sample with TiCl3 (b) or TiF3 (c).

References [1] Ronnebro et al; J. Phys. Chem. B Lett. 111

(2007) 12045 [2] Rongeat et al; submitted

Corresponding author: Carine Rongeat, email: [email protected], Tel. (+49) (351) 4659 669


42

THURSDAY

MORNING


43

FROM MICROSPOTS TO HYDROGEN STORAGE BY VIBRATIONAL SPECTROSCOPY

Andreas Borgschulte,1 Robin Gremaud,1 Motoaki Matsuo,2 Shin-Ichi Orimo,2 Andreas Züttel1 1Empa, Lab. Hydrogen & Energy, CH-8600 Dübendorf, Switzerland 2Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai, 980-8577, Japan

Raman spectroscopy on diffusion multiples (gradient samples) made of different hydrides and/or compounds is utilized as a high-through put method searching for new complex hydride phases. With studying the kinetics of formation of the various phases, the diffusion coefficients of the exchanged species can be determined. Particularly, the measurement of ion diffusivity in Li-based complex hydrides will help the search and development of fast lithium-ion conductors.

Introduction

In this work we give an overview how we use the investigation of vibrations in solids to gain valuable information on the functioning of hydrogen storage in complex hydrides and illustrate its prospect for further investigations. Particularly, we demonstrate the applicability of a novel high-throughput method using spatially resolved Raman spectroscopy.

Fig. 1. Hydrogenography by Raman By interdiffusion of different hydrides, samples with locally different compositions are obtained. Spatially resolved Raman spectroscopy allows the determination of possibly formed new phases in one single sample, and with further characterization the

corresponding pseudo-binary phase diagram is obtained. In addition, the kinetics of interdiffusion can be investigated.

Setup

For gradient samples, powder will be pressed into pellets. Pieces of these pellets made from different materials will then be sintered together at elevated temperatures. The thus prepared sample will be investigated by spatially resolved Raman spectroscopy (“hydrogenography”).

Applications

Tracer-Diffusion of hydrogen in complex hydrides, e.g. in LiBH4 [1]

Pseudo binary phase diagrams of complex hydrides, e.g. LiNH2-LiBH4 etc. [2]

Exchange of halide anions in complex hydrides, e.g. LiBH4-LiI, LiBH4-LiBF4. [2]

References [1] R. Gremaud et al. Phys. Rev. B 80, 100301(R)

(2009). [2] M. Matsuo,et al. J. Am. Chem. Soc., 2009,

131 (45), pp 16389–16391.

Corresponding author: A. Borgschulte, email: [email protected], Tel. (+41) (44) 823 4639


44

HYDROGEN DESORPTION MECHANISUMS AT THE SURFACES OF AlH3 AND LiBH4

Shunsuke Kato1, Michael Bielmann1, Kazutaka Ikeda2, Valentina Zakaznova-Herzog1, Arndt Remhof1, Shin-ichi Orimo2, Andreas Borgschulte1, Andreas Züttel1 1Empa Materials Science and Technology, Dept. Energy, Environment & Mobility, Laboratory for Hydrogen & Energy, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland. 2Tohoku University, Institute for Materials Research, Katahira 2-1-1, Sendai, 980-8577, Japan.

The surface processes of AlH3 and LiBH4 were investigated with repect to the surface oxidation and hydrogen desorption mechanims at the hydrides surfaces. The surface changes were systematically investigated by means of X-ray Photoelectron Spectroscopy, Thermal Desorption Spectroscopy and Mass Spectrometry. The surface condtion, i.e., surface oxide layer, singnificaly affects thier hydronge desorption kinetics.

Introduction

Under practical conditions, surface contamination of hydrogen storage material by impurity gasses has to be taken into account since the surface conditions are crucial for the hydrogen sorption kinetics [1, 2]. This study focuses on two different families of hydrides, namely, covalent-like and complex hydrides, AlH3 and LiBH4 respectively. The hydrogen desorption mechanisms at the hydrides surfaces were investigated.

Experimental

Surface changes of AlH3 during the hydrogen desorption. The surface changes were investigated by means of in situ X-ray Photoelectron Spectroscopy (XPS) combined with Thermal Desorption Spectroscopy (TDS) and Mass Spectrometry (MS). Surface oxidation study of LiBH4 and the hydrogen desorption kinetics. The clean surface was prepared, and subsequently modified by exposing to O2 with the amount of 3 L up to 107 L at 313 K (1 L = 10-6 Torrs). The induced surface changes were analyzed by XPS. The hydrogen desorption processes were studied by TDS and MS.

Results

A closed surface oxide layer prevents thermodynamically unstable AlH3 from the decomposition (as depicted in Fig. 1). The surface oxidation of LiBH4 reduces the diborane desorption and results in the enhanced desorption of hydrogen molecules from the surface oxide layer.

Fig. 1. Mechanism of hydrogen desorption from the surface of AlH3 (schematic). (a) inhibition of hydrogen desorption by surface oxide layers, e.g. Al2O3 (b) breaking of surface oxide layers (c) recombination of hydrogen and growth of metallic Al phase [1].

References [1] S. Kato, M. Bielmann, K. Ikeda, S. Orimo, A.

Borgschulte, A. Züttel, Appl. Phys. Lett. in press.

[2] A. Borgschlute, M. Bielmann, A. Züttel, G.Barkhordarian, M. Dornheim, R. Bormann, Appl. Surf. Sci. 254 (2008) 2377.

Corresponding author: Shunsuke Kato, email: [email protected], Tel. (+41) (44) 823 4327


45

TOWARDS SOLAR FUELS BY NOVEL PHOTOELECTROCATALYTIC APPROACH

Gabriele Centi and Siglinda Perathoner

Univ.of Messina and INSTM/CASPE (Lab. of Catalysis for Sustainable Production and Energy), Dip. di Chimica Industriale ed Ing. dei Materiali, Salita Sperone 31, 98166 Messina (Italy).

Solar fuels, in particular those obtained by converting CO2 to liquid fuels using water and solar energy, will be an important aspect of the future scenario for sustainable energy. After introducing possibilities and perspectives in solar fuels, the lecture will discuss more specifically the photoelectrochemical/catalytic (PEC) approach to solar fuels. It will be presented the concept of PEC reactor, which differentiates from the conventional ones. The same apparatus can be used also for a separate H2 and O2 production from water by photoelectrolysis (photosplitting) and for the H2 production by photoreforming. From CO2 it is possible to produce isopropanol using carbon nanotube based electrode.

Introduction

Producing solar fuels is a hot topic with large scientific and industrial interest, as well as great attention from the public [1]. There are many options, but the winning solution is still unclear. After introducing possibilities and perspectives in this field, and limits and constrains as well, the lecture will discuss more specifically an approach to solar fuels (photoelectrochemical/catalytic - PEC - conversion of CO2) which is considered the preferable, although highly challenging. The PEC solar cell differentiates from the conventional photoelectrochemical apparatus in terms of electrodes and operations in solventless conditions [2]. The same cell can be used also for the photoproduction of H2 from water and/or waste organics (photoreforming of bioethanol waste solutions). Isopropanol can be synthesized from CO2 using carbon nanotube based electrode.

PEC solar cell

For a practical use of PEC solar cells, the design should be quite different from that used typically in literature. The anode and cathode in the PEC device should be in the form of a thin film separated from a proton-conducting membrane (Nafion®, for example) and deposited over a porous conductive

substrate which allows the efficient collection/transport of the electrons over the entire film as well the diffusion of protons to/from the membrane. It is also necessary to allow an efficient transport of the gas. The PEC reactor shows analogies to PEM fuel cells. One side of the cell is composed by a nanostructured TiO2-based thin film where photo-electrolysis of water using solar light occurs. Protons diffuse through a membrane on the other side of the PEC device and react with CO2 in the presence of electrons (generated in water photodissociation; anode and cathode sides are connected by a wire) and a special electrocatalyst, based on the concept of nanoconfinement. The lecture will discuss aspects related to the preparation of the nanostructured titania thin film (photoanode) and its performances in the photoproduction of H2 (from water and alcohols), and of the preparation and performances of the carbon nanotube based electrode (cathode) for the reduction of CO2 to liquid hydrocarbons and alcohols.

References [1] Centi, G. et al; Solar production of fuels from

water and CO2. In Carbon-Neutral Fuels and Energy Carriers. Taylor & Francis (2009).

[2] Centi, G. et al.; Green Chem., 9 (2007) 671.

Corresponding author: Gabriele Centi, email: [email protected], Tel. (+39) (090) 6765609


46

CARBON DIOXIDE AS HYDROGEN VECTOR IN H2 STORAGE AND DELIVERY

Gábor Laurenczy École Polytechnique Fédérale de Lausanne (EPFL), SB ISIC LCOM, Lausanne CH-1015, Switzerland

The homogeneous catalytic decomposition of formic acid in aqueous solution provides an efficient in situ method for hydrogen production that operates over a wide range of pressures, under mild conditions, and at a controllable rate. A continuous high pressure hydrogen generator has been built, the catalyst remained active after a large number of times stopping and re-starting the process. In the HCOOH – CO2 cycle the greenhouse carbon dioxide gas is used as hydrogen vector.

Introduction

Hydrogen is the carrier of energy – the source of energy of the future. H2 is a versatile fuel for classical engines, gas turbines and fuel cells; having two problems: storage and delivery [1].

Experimental

The homogeneous catalytic decomposition of formic acid in aqueous solution have been carried out using hydrophilic ruthenium-based catalysts, generated from the highly water soluble ligand meta-trisulfonated triphenylphosphine (TPPTS) and RuCl3.

Results and conclusions

Formic acid (HCOOH) has the advantage over other organic molecules to decompose only into gaseous products (H2 and CO2), in a very selective homogeneous catalytic reaction, operating in environmentally friendly solvent, in water: a new catalytic system has been developed that efficiently and selectively generates high pressure hydrogen from formic acid [2-4]. Carbon dioxide can be recycled, reduced into formic acid electrochemically or by direct hydrogenation. These recent results concerning the homogeneous catalytic formic acid decomposition reactions have been considered as a breakthrough in the

hydrogen storage and delivery, making these systems suitable for practical applications [5].

Fig. 1. The “green” carbon dioxide – formic acid cycle.

Acknowledgment. Swiss National Science Foundation (FNS), Swiss Innovation Promotion Agency (CTI) and EPFL are thanked for financial support.

References [1] L. Schlapbach, A. Züttel, Nature, 414, 353

(2001). [2] C. Fellay, P. J. Dyson, G. Laurenczy,

International patent application (2006). [3] C. Fellay, P. J. Dyson, G. Laurenczy, Angew.

Chem. Int. Ed., 47, 3966 (2008). [4] C. Fellay, N. Yan, P. J. Dyson, G. Laurenczy,

Chem. Eur. J., 15, 3752 (2009). [5] F. Joó, ChemSusChem,1 805 (2008).

Corresponding author: Gábor Laurenczy, email: [email protected], Tel. (+41) (21) 693 9858


47

NEW CATALYSTS AND PROCESSES FOR AMINE BORANES AS CHEMICAL HYDROGEN STORAGE MATERIALS

Heinz Berke*, Yanfeng Jiang, Chunfang Jiang, Xinghua Yang, Olivier Blacque, Thomas Fox

University of Zurich, Institute of Inorganic Chemistry, Winterthurerstr. 190, CH-8057 Zürich, Switzerland

A new rhenium based catalyst for the dehydrogenation of ammonia borane and amine boranes is presented leading to borazine or cycloborazanes, respectively. Furthermore a new prototypical reaction of ammonia borane with imines was studied bearing great potential for improvement of the dehydrogenation selectivities concerning the boron/nitrogen products.

Introduction

Various Amine boranes possess high theoretical hydrogen storage capacities. Their practical application is however often hampered by irreversibility of hydrogen release (“fuelling”) or up-take (“refuelling”) or by low selectivities for these processes leading to a plethora of complex compounds. These deficiencies are thought to be resolvable by the involvement of catalysts or by development of new “fuelling” or “refuelling” processes. Catalytic approaches have been pursued in particular for the dehydrogenation of ammonia borane (H3B-NH3), however, mainly noble metal catalysts were found to be active enough to establish reasonable reaction rates and temperatures and also acceptable selectivities [1].

Experimental and Results

Our group has studied a rhenium based dehydrogenation catalysis of ammonia borane and methyl amine boranes and found relatively selective processes operating at 60-80°C[2].

Me2NH•BH3

cat.[Me2N-BH2]2

NH3•BH3

cat.[H2N-BH2]n

- H2

- H2

[HN=BH]3- H2

1/2

1/n 1/3

Re

Br

NO

R3P H

PR3

cat. =

cat.

Quite remarkable is the high selectivity for the formation of borazine and cycloborazanes, respectively. Mechanistic studies revealed involvement of rhenium mono-phosphine complexes. The reaction was found to be half order in the imine and first order in ammonia borane. Furthermore, we explored the possibility to apply a “metal-free” transfer hydrogenation between ammonia borane and imines producing amines and [BH2=NH2] as a primary intermediate[2].

H3B NH3R

HC

NR'

R

H2C

NH

R'H2B NH2

HN

HBNH

BH

NH

HB

+

1/3

Slow

Fast

+

R

H2C

NH

R'+or Polyborazylene

Detailed deuterium isotope studies revealed kinetic isotope effects, from which a concerted mechanism in the form of a double H transfer was concluded. Further studies will be devoted to the use of imines with diminished hydrogenation enthalpies to establish reversibility of the process.

References [1] Hamilton et al; Chem. Soc.Rev. 38 (2009) 279; Stephens et al; Dalton Trans. 25 (2007) 2613 [2] Berke, Chem. Com. (2007) 3571-3573;

Berke et al; Organometallics 28 (2009) 5493 [3] Berke et al; Angew. Chem. Int.,(2009) subm.

Corresponding author: Heinz Berke, email: [email protected], Tel. (+41) (44) 635 4680


48

KEMERIT – CARBON MATERIAL FOR ENERGY APPLICATION

Alexey Kozlov1, Chingiz Barnakov1, Zinfer Ismagilov2

Institute of Coal and Coal Chemistry SB RAS, Pr. Sovetskiy 18, Kemerovo, 650099, Russia Boreskov Institute of Catalysis SB RAS, Pr. Ak. Lavrentieva, 5, Novosibirsk, 630090, Russia

The samples of amorphous carbon material (ACM) were prepared from different precursors by thermo-catalytic synthesis (heat treatment of precursor and reactant mixture in inert atmosphere at temperature of 600-800C). The surface area of the samples was varying from 1000 to 3000 sq.m./g, micropore volume of the samples was varying from 0.5 to 1.6 cub.cm/g. It was established that the best hydrogen storage capacity of the samples is 5.5 wt % at 4 MPa and 77 K and the best methane storage capacity of the samples is 25 wt % at 4 MPa and 273 K. Application of ACM sample as support for proton exchange membrane fuel cell cathode catalysts exhibits better performance compared with commercial Vulcan XC-72R.

Introduction

The purposes of this paper are summarizing our results connected with synthesis and properties of ACM and discussion new data obtained for the last time.

Experimental

Coal, coal coke, petroleum coke, phenol, alizarin, 8-quinolinol, nitroaniline, 1,2,3-benzotriazol and other organic compounds were used as precursors of ACM samples. Detailed description of the synthesis was presented in patent [1].

Results

The adsorption of CH4 and H2 was studied with a high-pressure volumetric device designed for the purpose. The data for the several ACM samples are collected in Table 1. It is revealed that H2 storage by adsorption on the ACM samples as well as on AX-21 is considerable only at temperature of 77 K and value of CH4 adsorption is up to 25 wt.% at temperature of 273 K and pressure of 4 MPa. In paper [2] ACM sample was used for synthesis of platinum cathode catalysts for proton exchange membrane fuel cells. Investigations were conducted on ACM sample prepared from petroleum coke. Platinum particles were deposited on the sample with using of special method.

Commercial Vulcan XC-72R support was used as comparing sample. The membrane electrode assembly testing showed that the Pt cathode catalysts on ACM exhibit better performance in comparison with a catalyst on conventional carbon black support Pt/Vulcan XC-72R. Table 1. Textural and adsorption characteristics of ACM samples

Precursor ABET/A,

m2/g VS/V, sm3/g

H2, wt.%

CH4, wt.%

АХ-21 2800/2680 1.60/1.20 5.1 17.2 Coal “D mark” 3100/2960 1.55/1.08 3.5 12.8 Petroleum coke 3200/3050 1.62/1.12 4.5 15.8 Phenol 2240/1871 1.53/0.98 5.0 17.0 8-quinolinol 2550/2235 1.59/1.21 5.2 18.0 m- nitroaniline 2970/2780 1.86/1.57 5.5 25.5 ABET – BET surface area, A – micropore surface area, VS – total pore volume, V – micropore pore volume, H2 – H2 adsorption at 77 K and 4 MPa, CH4 – CH4 adsorption at 273 K and 4 MPa. This work was carried out at financial support of the RFBR (project no. 07-03-96042) and the Russian Science Support Foundation.

References [1] Barnakov Ch.N. et al. Patent RU2206394 [2] Z.R. Ismagilov, et al. Catalysis Today, 102–

103 (2005) 58.

Corresponding author: Alexey Kozlov, email: [email protected], Tel. (+7) (3842) 368188


49

A MULTIDISCIPLINARY, BIOLOGICAL APPROACH USING SOLAR ENERGY TO CAPTURE CO2 WHILE PRODUCING H2 AND HIGH VALUE PRODUCTS

Jiri Muller

Institutt for Energiteknikk, Kjeller, Norway

Many areas of algae technology have been developed over the last decades, and there is an established market for products derived from algae, dominated by health food and aquaculture. In addition, the interest for active biomolecules from algae is increasing rapidly. The need for CO2 management, in particular capture and storage is currently an important technological, economical and global political issue and will continue to be so until alternative energy sources and energy carriers diminish the need for fossil fuels. This presentation summarizes in an integrated manner different technologies for use of algae, demonstrating the possibility of combining different areas of algae technology to capture CO2 and using the obtained algal biomass for various industrial applications thus bringing added value to the capturing and storage processes. Furthermore, we emphasize the use of algae in a novel biological process which produces H2 directly from solar energy in contrast to the conventional CO2 neutral biological methods. This biological process is a part of the proposed integrated CO2 management scheme.


FROM HYDRIDES TO SYNTHETIC FUELS

Andreas Züttel, Shunsuke Kato, Oliver Friedrichs, Andreas Borgschulte

Empa Materials Science & Technology, Dept. Energy, Environment and Mobility, Div. Hydrogen & Energy, CH-8600 Dübendorf, Switzerland

The natural energy cycle is based on the photosynthesis of the plants. The solar light as the energy input allows the dissociation of water into hydrogen and oxygen (light cycle). The hydrogen is the used to reduce the absorbed CO2 to carbohydrates (dark cycle). Finally, the carbohydrates are converted in a very slow anaerobic process into hydrocarbons, i.e. the fossil fuels. Electricity produced by photovoltaics can be used in an electrolyzer for the production of hydrogen. The CO2 from the atmosphere is the reduced with the hydrogen be the inverse watergas shift reaction and the Fischer-Tropsch synthesis to hydrocarbons.

Energy density

The hydrogen density of hydride materials is, based on to today’s knowledge, limited at 150 kg H2/m

3 and 20 mass%. This corres-ponds to an energy density of 5800 kWh/m3 and 7.8 kWh/kg, which is about 60% of the energy density of petrol. This value is based on the materials only and drops to <10% for the comparison of storage systems.

Liquid hydrides

Some complex hydrides are liquid at room temperature e.g. Al[BH4]3. Furthermore, the less stable hydrides also exhibit fast hydrogen desorption rates. Therefore, liquid complex hydrides may have advantages for the application as compared to the salt like solids, e.g. the handling, the mass transport, the thermal conductivity. Several liquid hydrides are identified and there properties analyzed.

Synthetic fuels

Hydrogen reacts with carbondiaxid to carbonmonoxid in the reversed watergas-shift reaction:

CO2 + H2 CO + H2O H = -2.8 kJ/mol

Furthermore, syngas CO + H2 then reacts to synthetic hydrocarbons by the Fischer-Tropsch synthesis:

n CO + (2n+1) H2 CnH2n+2 + n H2O

at 1 bar and 160 - 200°C. The enthalpy of the reaction is for octane H(n=8) = -1685 kJ/mol Oktan. The upper heating value of octane is HC = -5430 kJ/mol.

Fig. 1. Synthetic fuel cycle.

The cycle conserves thermodynamically 60% of the electrical energy in the form of hydrocarbons.

References [1] A. Züttel, Philosophical Magazin (2009), in

press

Corresponding author: Andreas Züttel, email: mailto:[email protected], Tel. (+41) (44) 823 4038

50


51

THURSDAY

AFTERNOON


52

INVESTIGATION OF HYDROGEN STORAGE ALLOYS AND THEIR APPLICATION TO ON-BOARD STORAGE TANK

Etsuo Akiba, Kohta Asano, Shigeru Tsunokake*, Tatsuya Fuura*, Yoshiki Sakaguchi** Masanori Monde**

AIST, Tsukuba Central 5, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8565 Japan. *Japan Metals & Chemicals Co., Ltd., 232 Oguni Oguni-machi, Nishiokitama-gun, Yamagata 999-1351, Japan. **SAMTEC Co. Ltd., 1000-18, Enmeicho, Kashiwabara, Osaka, 582-0027, Japan. *** Saga University, 1 Honjo, Saga, 840-8502, Japan.

Under a national project since 2005, we have developed a hybrid tank system for on board hydrogen storage as well as Ti based BCC alloys for hybrid tank system. Fabrication technologies of the hybrid tank have been developed. Ti-Mn-V alloys developed contained 2.8 mass % of hydrogen. Modelling of the tank has also investigated for improvement of tank design. Introduction

Major on board hydrogen storage methods are compressed gas, liquid hydrogen and hydrogen storage materials. However, at present any of single methods meet the requirements from vehicular application. The hybrid tank system is combination of hydrogen storage materials and compressed gas. Takeichi et al. [1] have proposed the concept of the system and demonstrations using real size tanks have been carried out by Toyota Motor Co [2]. Development of the tank system has been conducted under the Japanese national project and materials for the hybrid tank are also investigated. In the hybrid tank, hydrogen pressure reaches to 35 MPa in some cases but there is little work in this pressure region so far. In this paper, recent progress in fabrication of the hybrid tank and in material investigation is introduced.

Experimental

The Ti-V-Mn alloys with BCC structure were prepared using arc melting method. The alloys produced are used for hydrogenation as is. X-ray diffraction and the Rietveld analysis using RIETAN software were carried out.

Results

It was found that the relation of chemical composition of alloys and lattice parameter. Lattice parameter linearly related to hydrogen equilibrium pressure. It means that we established the design concept of Ti-V-Mn alloys. According to the concept, hydrogen capacity of 2.8 mass % has been realized. For hybrid tank development, we have firstly established the original design of the tank based on modelling and developed manufacturing method. Figure 1 shows the concept of hybrid tank developed.

Fig. 1. Concept of hybrid tank.

References [1] N. Takeichi et al; Int J. Hydrogen Energy. 28

(2003) 1121 [2] D. Mori et al; Proceedings of MH2008 (2008)

Corresponding author: Etsuo Akiba, email: [email protected], Tel. (+81) (298) 61 4541


53

A METAL HYDRIDE AS A MEANS OF ENERGY STORAGE IN A CANAL BOAT

Alex Bevan, David Book, Andeas Züttel* and Rex Harris

School of Metallurgy and Materials, University of Birmingham, UK. *Empa Materials Science and Technology, Switzerland.

This paper describes the application of a large- scale (~240 kg) metal hydride store as a means of energy storage on board a converted canal boat. The standard diesel engine was replaced by a 10kW NdFeB permanent magnet electric motor together with a lead-acid battery stack and a 1kW PEM fuel cell supplied by pure hydrogen from metal hydride powder contained within stainless steel tubes.This store provided substantial additional electric energy storage and was the most expensive element in the conversion process. Thus the performance of this store was of particular significance and is the main subject of this paper. Introduction Hydrogen has considerable potential as an effective means of storing electricity which, in transportation, can be converted into traction by means of a PEM fuel cell and an electric motor. If the hydrogen is generated and distributed by means of low (or zero) carbon technologies, then this provides an effective means of reducing the carbon footprint of long-range transportation. One of the major challenges to the introduction of this technology is the mobile storage of the hydrogen with sufficient gravimetric and volumetric density. Consequently there is considerable effort on the development of light-weight, solid-state hydrogen stores but, for road transport, the favoured choice at this juncture is high pressure (~700bar) hydrogen storage in light-weight composite tanks. In the case of water-based transportation however, the storage requirements are much more relaxed and conventional metal hydrides can be employed as a practical means of solid state hydrogen storage. This option has been explored in the current project and this paper describes the preliminary findings on a converted electric canal boat.

Experimental A standard British Waterways (BW) maintenance canal boat was kindly provided by BW and this was converted to the current vessel (the Ross Barlow*) over a period of around 2 years. The diesel engine (~15kw) was removed and the space converted to accommodate a 10kW NdFeB

based motor and a lead-acid battery stack. The conventional tiller was also supplemented with NdFeB actuated power steering. This provided the possibility of remote operation of the vessel. At the other end of the boat the space was adapted to accommodate the stainless steel hydrogen storage system, hydrogen delivery and flow measurement facilities and the 1kW PEM fuel cell (Reli-On). These units were accommodated in a well ventilated space with an explosion hatch at the front of the boat together with hydrogen detectors. The storage unit could be charged from external hydrogen cylinders on the bank of the canal and the water temperature was regulated by a heat exchanger via the canal. Laboratory equipment was also constructed to cycle automatically the hydrogen storage material so that accelerated ageing trials could be carried out.

Results The Ross Barlow has been subject to extensive trials and, overall, the experience has been very encouraging and largely trouble-free. The hydrogen store has performed extremely well and there has been no observable decrease in the storage capacity or in the kinetics of hydrogen absorption or desorption. It was also decided to subject the storage alloy (based on the Laves compound TiMn2 with ~1.9wt% H2) to some accelerated ageing trials in the laboratory. The results of these investigations are reported in this paper

*Named after a post graduate student who died in 2005. Corresponding author: Rex Harris, email: [email protected] . Tel + 44 (0)121 414 5165


54

HYDROGEN CYCLE FOR A SELF-SUFFICIENT ACCOMODATION UNIT (SELF) U. Vogt1, M. Bielmann1, V.Zakaznova-Herzog1, M. Zimmermann2, S. Machini2, B. Olsson2, A. Züttel1 1Empa Materials Science and Technology, Dept. Energy, Environment & Mobility, Sec. Hydrogen & Energy, CH-8600 Dübendorf, Switzerland 2Empa Materials Science and Technology, Dept. Civil and Mechanical Engineering, Sec. Building-Technologies, CH-8600 Dübendorf, Switzerland

The aim of the project SELF is to build up a self sufficient accommodation unit for independent living, working or research on nearly any place in Europe. For that reason, it has to be assured that the unit can be transported by helicopter or track to the places of use. Outside the civilisation SELF will attain energy and water from the environment, storage it and thus represent an energy-independent living and modern prospective building concept with a stand-alone power system (SAPS). Energy concept

Electricity will be gained by PV, stored in Li-ion batteries and used for daily purposes, light and controlsystem of the unit. As the dimension of the PV facilities will be designed for sufficient power supply in wintertime, it will produce excess electricity during summertime which cannot be stored in batteries. Surplus energy will be transformed into hydrogen by an electrolyser and stored in metal hydrides. The hydrogen will be used for cooking and heating during wintertime. For this purpose, a new type of catalytic porous burner will be developed, which can convert the energy, stored as hydrogen, very efficient in heat without any pollutions like CO2 or NOx. The only reactant will be water which is even beneficial for the room climate. The water electrolysis and hydrogen storage is superior compared to long term electricity storage regarding storage density, storage volume and storage weight.

H2 electrolysis and storage

Hydrogen synthesis by electrolysis from water and electrical energy will produce only H2 and O2 without any exhaust gases. The H2 production will be carried out from excess energy during summertime by a commercial electrolyser with a production rate of 1l/min. The total hydrogen production is calculated

to be 3.8 to 4.5 kg during 100 days of operation. For hydrogen storage, metal hydrides will be used supported in metal tanks. The total weight for H2 storage is limited to 320 kg.

Concept of H2 synthesis and storage

Catalytical H2 burner

A self-igniting catalytic H2 diffusion burner based on porous ceramics will be developed for cooking and heating. This ensures a very high safety aspect and can be used safe also in closed rooms, as no waste gases will be released.

Reference U.P. Grossmann, J. Lehmann, F. Menzl, A non-stationary hydrogen cooker with portable hydride storage and catalytic hydrogen burner, Int. Journal of Hydrogen Energy 25 (2000) 87-90

Corresponding author: Ulrich Vogt, email [email protected]


55

SYNTHESIS AND PROPERTIES OF LiBH4-Mg(BH4)2

NANOCOMPOSITES

Elisa Gil Bardají, Maximilian Fichtner

Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology, P.O. Box 3640, D-76021 Karlsruhe, Germany

Mixed-metal borohydride LiMg(BH4)x has been synthesized either by ball milling or by the reaction of the single borohydrides in an organic solvent. The resulting LiBH4-Mg(BH4)2 nanocomposite has been investigated by X-Ray Powder Diffraction (XRD), High Pressure Differential Scanning Calorimetry (HP-DSC) and Thermogravimetric Analysis (TGA). The thermal properties of the material remarkably differ from the properties of the starting materials.

Introduction

Recently, it has been proposed that mixed-metal borohydrides based on alkali and selected transition metals could have acceptable thermodynamics for reversible hydrogen storage and still maintain a high hydrogen capacity.1 Additionally, first reports on bialkali borohydrides, such as LiK(BH4)2

2 and NaK(BH4)2,

3 have been published. In the case of LiBH4-Ca(BH4)2 nanocomposite4 even a partial reversibility has been confirmed for the first time in the case of a mixed borohydride composite. This work deals with the LiBH4-Mg(BH4)2 system.

Experimental

A 1:1 mixture of LiBH4 and Mg(BH4)2 was ball milled in Fritsch P6 planetary mill. Subsequently, diethylether was added to the product and the suspension was stirred overnight, under reflux. Following extraction of the solvent led to the formation of a white powder, which was dried under vacuum. Both as-milled as well as as-synthesized materials were investigated by x-ray powder diffraction and thermal analysis.

Results

The thermal decomposition properties of the resulting material are remarkably different from those of each single borohydride. For instance, the differential scanning calorimetry

(DSC) profile of the as-milled material [LiBH4-Mg(BH4)2] is showed in Figure 1. Three endothermic peaks appear below 200°C followed by a broad exothermic contribution and finally two additional endothermic events. Remarkably, the melting point peak of LiBH4 at ca. 280°C can not be detected.

50 100 150 200 250 300 350 400 450 500-1

0

1

2

3

4

5

6exo.

Inte

nsi

ty(m

W/m

g)

Temperature(°C)

Fig. 1. DSC profile of as-milled LiBH4-Mg(BH4)2 nanocomposite under 5 bar H2 at a heating rate of 5 K/min..

References [1] Li et al., J. Alloys Compd.,315, 2007, 446. [2] Nickels et al; , Angew. Chem. Int. Ed., 47,

2008, 2817 / Xia et al., J. Phys.: Condens. Matter.,20,2008,445210.

[3] Seballos et al., J. Alloys Compd., 476, 2009, 446. [4] Lee et al., J. Phys. Chem. C ,113, 2009, 15080

Corresponding author: Elisa Gil Bardají, email: [email protected], Tel. (+49) 7247-82-8909


56

PELLETS OF MgH2-BASED COMPOSITES AS PRACTICAL MATERIAL FOR SOLID STATE HYDROGEN STORAGE

Giovanni Principi1, Ashish Khandelwal1, Filippo Agresti1, Giovanni Capurso1, Amedeo Maddalena1, Sergio Lo Russo2 1 Università di Padova, Dipartimento di Ingegneria Meccanica,Settore Materiali, via Marzolo 9, 35131, Padova, Italy. 2Università di Padova, Dipartimento di Fisica and CNISM, via Marzolo 8, 35131, Padova, Italy

Hydrogen absorption/desorption (a/d) properties and mechanical stability of pellets made of compressed ball-milled MgH2 powders mixed with catalysts (Nb2O5 and graphite) and a binding agent (aluminium powder) have been investigated. The best cycling behaviour and mechanical strength stability have been observed for pellets of catalyzed MgH2 powders added with 5 wt% aluminium annealed in vacuum at 450 °C before starting the a/d cycles. This mechanical stability to cycles has been attributed to the formation of a solid solution of aluminium in magnesium.

Introduction

During scaling up studies of MgH2 based powders in a specially designed reactor it was observed that the hydrogen storage capacity as well as the a/d kinetics decreased with the ongoing cycles due to a close compaction of the powder particles inside the reaction chamber associated with local overheating [1]. These observations motivated us to study MgH2 based powders moderately pressed in the form of pellets with the addition of some binding agent in order to retain stable mechanical consistency and structure with persistent free paths for hydrogen diffusion.

Experimental

MgH2 powder was ball milled with Nb2O5 (5 wt %) and graphite (1 wt%) in a SPEX 8000 shaker mill for 20 hours using steel balls with ball to powder ratio of 10:1. The pellets of milled powder with and without aluminum powder were prepared by pressing the powders in Ar atmosphere with a uniaxial pressure of 180 MPa by means of an Instron 1121 tester. Structural characterization was done by X-ray diffraction. Kinetic and thermodynamic tests were performed using a Sievert’s type gas reaction controller. The tests for compressive strength resistance of the pellets were performed using the same Instron 1121.

Results

It is found that a pre-heating treatment of the pellet to the temperature sufficient to form intermetallic phases and/or solid Mg-Al solutions (450 °C) increases the resulting performance of the material, as concerns both functional and mechanical stability. A good mechanical stability has been observed in the case of pellets with 5 wt% Al. These pellets show a constant 5.3 wt% hydrogen capacity up to 50 cycles and constant kinetics after 10 cycles.

Fig. 1. Pictures of the pellets after different cycles

The enhanced stability of the pellets in this case has been attributed to the presence of the Al in solid solution with Mg.

[1] Verga et al; Int. J. Hydrogen Energy 34(2009)4602.

Corresponding author: Giovanni Principi, email: [email protected], Tel. (+39) 049 827 5513


57

FRIDAY


58

EXPERIMENTAL RESULTS AND SIMULATIONS OF A LAB- SCALE HYDROGEN STORAGE TANK BASED ON NaAlH4.

Inga Utza, Farida Joppicha, Antje Wörnera, Maximilian Fichtnerb, Oleg Zabarab aDLR Deutsches Zentrum für Luft- und Raumfahrt, ITT, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany. bInstitute for Nanotechnology, Forschungszentrum Karlsruhe (KIT), Herrmann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany

Experimental results of absorption and desorption reactions of cerium-doped NaAlH4 in an air-heated tank are presented. With a hydrogenation pressure of 100 bars a maximum capacity of 3.5 wt% is reached after 4 h during absorption experiments. For desorption, after 5 h reaction a capacity of 3.5 wt% is reached at a pressure of 4 bars and 150°C. Additionally, the kinetics of the material and the tank geometry have been modelled and the influence of cooling heat transfer and inlet hydrogen temperature are analyzed.

Introduction

In this work absorption and desorption reactions of 300 g cerium-doped sodium alanate provided by KIT have been tested in a lab-scale test-setup. The material has been chosen as it proves high hydrogen capacitiy and good cycling stability [1]. The hydrating and dehydrating reaction of doped sodium alanate proceed in two steps with a required temperature for absorption of ~80 and for desorption of ~150°C. 1st step: 3 NaAlH4 ↔ Na3AlH6 + 2 Al + 3 H2

2nd step: Na3AlH6 ↔ 3 NaH + Al + 3/2 H2. The tank model used in this work is based on a model for LaNi5 [2] and has been extended to these two-step kinetics of sodium alanate.

Experimental

Fig. 1. Experimental test-setup, reactor on the left.

In the newly-built experimental setup, the tank is heated with air from a blower and for absorption, the H2 is pre-heated by a thermostatic bath. The flow rate for desorption and absorption reactions can be either flow or pressure controlled.

Results

The experimental charge- discharge cycles of the air-heated tank (diameter: 43 mm) show good reproducibility. For the absorption reaction ~2 wt% H2 have been stored in 30 min and a total capacity of 3.5 wt% has been reached in 4 h. Desorption results show a capacity of 3.5 wt% in 5 h. Simulations show for low inlet and air temperatures high rates in the beginning of an absorption, as the reaction heat is removed quickly. However, as the kinetics of the material are rather slow, in the end of the reaction the absorption heat is marginal, the tank gets cool and the reaction slows down. Thus, by increasing the air temperature during the reaction one can achieve fast absorption times.

References [1] Bogdanović et al; J. Alloys Compd. 471(2009)

383 [2] Coutourier et al; Proceedings of the ASME

ES2008-54031

Corresponding author: Inga Utz, email: [email protected], Tel. (+49) (711) 6862 492


59

CORRELATION BETWEEN MORPHOLOGY, WATER UPTAKE, AND PROTON CONDUCTIVITY IN RADIATION GRAFTED PROTON EXCHANGE MEMBRANES

S. Balog1, U. Gasser1,2, K. Mortensen3, L. Gubler4, H. Ben youcef4, and G. G. Scherer4 1Laboratory for Neutron Scattering, ETH Zurich & Paul Scherrer Institut, Switzerland 2Adolphe Merkle Institute, University of Fribourg, Switzerland 3Department of Natural Sciences, University of Copenhagen, Denmark 4Electrochemistry Laboratory, Paul Scherrer Institut, Switzerland An SANS investigation of hydrated proton exchange membranes is presented. To understand the relationship between morphology, water uptake, and proton conductivity, we applied the technique of contrast variation. Introduction

Our membranes were synthesized by radiation-induced grafting of poly(ethylene-alt-tetrafluoroethylene) (ETFE) with styrene in the presence of crosslinker (divinylbenzene, DVB), and by sulfonating the polystyrene. Crosslinking highly influences the fuel cell relevant properties. We report on the domain structure, focusing on the impact of crosslinking on the relationship between the domain structure, water uptake, and proton conductivity.

Experimental

SANS contrast variation method was used. The ion exchange capacity, proton conductivity, water uptake, and hydration number were characterized using our standard procedures.

Results

The membranes are separated into two phases. The amorphous phase hosts the water and swells upon hydration, swelling being inversely proportional to the degree of crosslinking. Hydration and proton conductivity exhibit linear dependence on swelling. Proton conductivity and volumetric fraction of water are related by a power law

(Fig. 1.), indicating a percolated network of finely dispersed aqueous pores in the hydrophilic domains.

101 102

101

102

103

a

b

cde

f

cros

slink

leve

l incr

ease

s

[m

S c

m-1]

volume fraction of water [%]

Fig. 1. Proton conductivity versus volume fraction of water in the hydrated membranes. The crosslink level is a.) 0%, b.) 5%, c.) 8%, d.) 10%, e.) 15%, f.) 20%.

References [1] S. A. Guersel et al. Radiation grafted membranes. Fuel Cells I, vol. 215 of Advances in Polymer Science, pages 157-217. [2] L. Gubler et al. Radiation-grafted proton conducting membranes. Handbook of Fuel Cells: Advances in Electrocatalysis, Materials, Diagnostics and Durability, vol. 5 & 6

Corresponding author: Sandor Balog, email: [email protected], Tel. (+41) (56) 310 5586

4th

Hydrogen & Energy Symposium Wildhaus, Switzerland 2010

60

HYDROGEN PRODUCTION BY ALKALINE ELECTROLYSIS:

SURFACE AND ELECTROCHEMICAL INVESTIGATIONS OF

MATERIALS FOR DIAPHRAGMS

V. Zakaznova-Herzog1, N. Xanthopoulos2, J. Stojadinovic1, B. Fumey1, M. Gorbar1, D. Wiedenmann1,3, B. Grobéty3, U. Vogt1, A. Züttel1

1Empa Materials Science and Technology, Dept. Energy, Environment & Mobility, Sec.

Hydrogen & Energy, CH-8600 Dübendorf, Switzerland

2Laboratoire Analyse des Surfaces, EPFL-SB-CIME, CH-1015 Lausanne, Switzerland

3University of Fribourg, Dept. of Geosciences, Chemin du Musée 6, Pérolles, CH-1700 Fribourg

Production of hydrogen using high pressure alkaline electrolysis is well established and allows obtaining high purity pressurised hydrogen and oxygen gases. The electrolyser’s efficiency depends significantly on the ion-conductivity of diaphragms/membranes separating oxygen and hydrogen. Currently used diaphragms are made of asbestos, which are not only prohibited by recent health regulations, but also require high energy consumption. Therefore, we are looking for a new material to substitute asbestos which has an equal or even better performance. High gas purity, i.e., low gas penetration, is achieved through the small size of pores which is smaller than the hydrogen and oxygen bubbles. High ionic conductivity in asbestos is mainly achieved through its excellent wettability, the effects related to the fibrous structure and the specific porosity. The aforementioned properties most probably with the interplay of surface processes influence the ion conductivity. We report our first results of X-ray photoelectron spectroscopic study of pristine and reacted asbestos diaphragms and olivine mineral (Mg2SiO4) in 25% KOH at ambient conditions. The data combined with impedance measurements and tests in the electrolysis cell will allow the evaluation of new possibilities materials for new diaphragms.

Idea

Chrysotile mineral is known for its high ion conductance and gas tightness combined with high resistance to bases and acids, good flexibility and robustness. Qualitatively it can be explained by the special chemical composition (Mg silicate and OH group) but also the crystal structure (giving the presence fibres and pores). Some of silicate minerals of serpentine group have also the fibrous structure of asbestos, but contain other additional to Mg cations (like Al, Na, Fe etc) and can not be directly used as a substituting material. Other available Mg-silicate minerals don’t have a fibrous crystal structure. Recent XPS study of leaching of Mg silicate minerals revealed the presence monolayer OH

-

coverage on surface [1]. These surface complexes appear to be stable in the high vacuum XPS. Considering this new information, we can purposely create high surface area mineral membranes that have OH group presented on the surface comparable to asbestos surface.

Results

In the present study, we collected XPS spectra of pristine and used asbestos diaphragm and from the olivine freshly fractured and exposed to 30% KOH solution. at ambient conditions. The survey XPS spectra reveal strong changes in surface composition due to the reaction with KOH. The changes in oxygen chemical state on the surface can be detected from high resolution O 1s spectra and show an additional contribution (up to 10%). The position and the line width of the additional oxygen contribution species are similar to the observed previously OH- species.

References

[1] Zakaznova-Herzog V.P., H.W. Nesbitt, G.M. Bancroft and J.S. Tse. (2008) Geochim. Cosmochim. Acta 72, 69-86

Corresponding author: V. Zakaznova-Herzog, email: [email protected], Tel. (+41) (44) 823 4352


61

FIRST-PRINCIPLES INVESTIGATIONS OF HYDROGENATION PROCESS OF GRAPHENE: IN CONTEXT OF HYDROGEN STORAGE

Jieun Cho, Seok Ho Lim, Noejung Park

Department of Applied Physics, Dankook University, Yongin-si, 448-701, Korea

We use density-functional theory methods to investigate the energetics related to hydrogenation of graphene fragments. This work is motivated by recent experimental assertions that hydrogen spills over from metal catalyst to bridged carbon surfaces and a substantial amount of storage can be attained in room temperature. Concerned with doubt regarding those suggestions, we try to answer three questionable points: the thermodynamic stability of chemisorbed hydrogen atoms on graphene, the feasibility of hydrogen diffusion through the sp2-bonded carbon surface, and the effect of metal particles regarding whether the presence of metal particles can stabilize the hydrogen chemisorptions and lower the diffusion barrier. Unlike previous models, our results suggest that the pure carbon surface can not be an appropriate receptor for room temperature hydrogen storage, even though the spill-over to an unexplored surface might deserve further investigation in pursuit of room temperature hydrogen storage.

Introduction

Hydrogen has been considered an ideal fuel for renewable energy because it is abundant on Earth, and its oxidation product, which is nothing but water, is environment-friendly and completely harmless. However, how to store enough amount of hydrogen remains a big challenge and needs a breakthrough. During recent years, a new class of sorbent materials has been explored using the approach of the so-called hydrogen spillover. The spillover phenomenon can be defined as dissociative chemisorptions of hydrogen molecules on metal catalyst and subsequent migration or surface diffusion of the atomic hydrogen onto the support surfaces. Some research group claimed that a few weight percents of hydrogen can be reversibly stored into carbon material near room temperature through the spillover phenomena. In the present work, we investigate the feasibility of hydrogen spillover onto the carbon-based receptor.

Experimental

To obtain the geometries and energetics of adsorption and desorption reactions of

molecular hydrogen, density functional theory (DFT) calculations were performed with the generalized gradient-corrected approximation (BLYP). Local minimum structures and minimum energy reaction paths were determined. All calculations reported were obtained with the Vienna Ab initio Simulation Package (VASP) and NWchem package.

Results

In consistence with previous works, we found that hydrogen chemisorptions onto carbon surface can satisfy thermodynamic requirement for room temperature hydrogen storage if an appropriately-sized predefined sp3 region is provided. However, the barrier for migration of chemisorbed hydrogen was found to be too high. The barrier calculated with DFT/GGA/BLYP method is found to be around 0.8 eV. This indicates that the sp2 carbon surface can be a proper receptor for room temperature hydrogen storage. We suggest that surfaces with lower diffusion barriers should be provided in order for the spillover to be used in hydrogen storage near room temperature.

Corresponding author: Noejung Park, email: [email protected], Tel. (+81) (031) 8005 3208


62

OPTIMIZATION OF METAL DISPERSION AND HYDROGEN ADSORPTION IN DOPED GRAPHITIC MATERIALS FOR HYDROGEN STORAGE

Gyu-Bong Kim1, Noejung Park2, and Seung-Hoon Jhi1 1Department of Physics, POSTECH, Pohang 790-784, Republic of Korea, 2Dept. Applied Physics, Dankook University, Yongin 448-701, Republic of Korea

The non-covalent hydrogen binding on metal atoms dispersed on carbon clusters and graphene is studied with the use of the pseudopotential density-functional method. Substitutional doping in graphenes is explored to control the ionic state of the metal atoms that plays a crucial role for dispersion and hydrogen adsorption. It is found that the presence of acceptor-like states in the absorbents is essential for enhancing the metal adsorption strength and for increasing the number of hydrogen molecules attached to the metal atoms. This finding enables the optimization of hydrogen adsorption and metal dispersion in graphitic materials, which is useful for developing solid hydrogen storage and efficient catalysts.

Introduction

The interaction of hydrogen molecules with metal atoms is a key physicochemical process involved in fuel cell catalysts and hydrogen storage. Transition metal complexes have been studied extensively in this respect as they were shown to be very promising in terms of hydrogen binding strength and storage capacity at ambient conditions. Here we study the dispersion of metal atoms in doped graphenes and the hydrogen adsorption on these metals with the use of ab initio methods.

Computational

The DFT calculations are performed using the spin-polarized pseudopotential total-energy method as implemented in the VASP package. To investigate the accuracy of the density-functional calculations, part of calculations are repeated using the MP2 in graphene clusters with various basis sets as implemented in NWCHEM packages.

Results

Boron-doped graphenes were found to be effective for dispersion of both alkaline-earth and transition metals and hydrogen

adsorption thereon. The H2 adsorption in such complexes exhibits a crossover between Kubas and multipole Coulomb interactions depending on the ionic state of metals and the number of adsorbed H2. Our study suggests that material characteristics such as doping conditions can be optimized utilizing such an understanding of the adsorption mechanism in metal-dispersed materials.

Fig. 1. Consecutive H2 binding energies to Mg- and Ca-C32−xBx complexes.

References [1] Kim et. al.; Phys. Rev. B 79 (2009) 155437 [2] Kim et. al.; Phys. Rev. B 78 (2008) 085408

Corresponding author: Seung-Hoon Jhi, email: [email protected], Tel. (+82) (54) 279 2094


63

A BRIEF REVIEW OF CYCLAM AND RELATED COMPLEXES OF NICKEL: HYDROGEN REDUCTION AND CARBON FIXATION

Andrew Churchard and Wojciech Grochala

ICM and Faculty of Chemistry, The University of Warsaw, Poland

The macrocyclic, tetraamine ligand, 1,4,8,11-tetraazacyclotetradecane, commonly referred to as cyclam, has shown itself to be a remarkably useful ligand. Beley et al1 were the first to show the surprisingly high efficiency of a reduced form of Ni(cyclam)2+ in catalysis of the electroreduction of CO2 in water. In 2006, Grochala2 noted the similarities between CO2 and H2 in Mulliken electronegativity and Pearson hardness, postulating that Ni(cyclam) complexes may be useful for reducing H2, and thus as catalysts in complex hydride hydrogen stores. In this contribution we will review selected literature, focusing mainly on nickel cyclam complexes, covering the concepts of hydrogen reduction and carbon dioxide fixation. We will also report on on our own work including the synthesis and characterisation of two Ni(cyclam)(BH4)2 isomers, see figure.

References [1]Beley et al; J. Chem. Soc., Chem Comm. 2 (1984) 1315 [2]Grochala, W; Phys Chem. Chem. Phys. 8 (2006) 1340

Corresponding author: Wojciech Grochala, email: [email protected], Tel. (+48) 22 554 0828


64

Al IN ZIF-8: ENCAPSULATING MAGIC Ewa Banacha, Hans Stila, Huub Kooijmana and Hans Geerlingsa, b

a Shell Global Solutions International BV, Innovation & Research, 1030 BN Amsterdam, the Netherlands b DelftChemTech, Materials for Energy Conversion and Storage, Delft University of Technology, 2600 GA Delft, the Netherlands Synthesis and characterization of a Al/ZIF-8 composites by applying the organometallic precursors is demonstrated. Since the crystal structure of ZIF-8 should be preserved as its cavities will serve as a matrix for aluminum nanoparticles , ( so called “magic clusters”) main focus is to find a suitable precursor. We have been able to identify amine-alane adduct: dimethylethylamine alane as the one which does not affect the structure of ZIF-8. Synthesized product is further analyzed by employing various analytical techniques.

Introduction

Zeolitic imidazolate frameworks (ZIFs) are a new class of nanoporous materials which consist of tetrahedral transition metal clusters (Co, In, Zn, etc.) linked by simple imidazolate ligands. Those materials exhibit a tunable pore size, possess exceptional chemical stability and the rich structural diversity of zeolites. ZIF-8 is a prototypical ZIF compound (Zn(MeIM)2, MeIM=2-methylimidazolate) with sodalite type of structure. In this project we focus on the Al/ZIF-8 system that has been prepared employing precursor chemistry originating from the metal organic chemical vapour deposition of metal thin films (MOCVD) to load nanoporous crystalline powder of ZIF-8 with aluminum nanoparticles to yield nanocomposites which could be used for reversible storage of hydrogen.

Experimental

Aluminum loaded ZIF-8 species were synthesized by a gas-phase loading and solution infiltration method using two types of organometallic compounds

(triethylaluminum and dimethylethylamine alane). In order to correlate the data sets from different microscopy methods with the electrochemical performance, new concepts for multi-scale characterisation have to be established. Results

Utilizing various analytical techniques (PXRD, ICP, TEM, solid state NMR) characterization and comparison of the products were conducted to reveal the most optimal way of preparation and the most suitable organometallic precursor. References [1] K.S. Park, et al, PNAS, 103, 2006, 27

[2] D.M. Frigo, et al, Chem. Mater., 6, 1994, 190

[3] H. Wu, et al, J. Am. Chem. Soc., 129, 2007, 5314

[4] B. Kiran et al., Phys. Rev. Lett. 98, 2007, 256802

[5] D.M. Cox et al., J.Phys.Chem. , 1988, 92, 421-429

Corresponding author : Ewa Banach, email: [email protected],


65

POSTERS

SESSION 1

MONDAY


66

IMPACT OF MULTI-SCALE PORE STRUCTURE ON ION CONDUCTIVITY OF ASBESTOS GAS SEPARATION DIAPHRAGMS FOR ALKALINE WATER ELECTROLYSIS

D. Wiedenmann1,2, L. Holzer2, M. Gorbar1,2, U. Vogt2, V. Zakaznova-Herzog2, A. Züttel2, B. Grobéty1 1University of Fribourg, Department of Geosciences, Pérolles, 1700 Fribourg, Switzerland 2Empa, Swiss Federal Laboratories for Materials Testing and Research, 8600 Dübendorf, Switzerland

High-pressure alkaline electrolysis is a very efficient method to produce hydrogen on an industrial scale. To ensure high gas purity, anode and cathode of the electrolysis cell are separated by a porous and ion conductive diaphragm, which prevents intermixing of produced hydrogen and oxygen. In the case of zero-gap geometry, a flexible asbestos tissue is used, as it easily can be installed between the electrodes without being damaged. In order to keep the cell resistance low, the ionic conductivity of the porous diaphragm is crucial. Thereby, the conductivity is related to the pore structure. The aim of this study is to characterize the multi-scale pore structure by means of tomography and to establish a link to the electrochemical cell performance.

Introduction

Due to recent health regulations, asbestos based gas separation diaphragms are ptohibited in new electrolysers. For the development of alternative material concepts a thorough understanding of the link between microstructure and cell performance is fundamental.

Experimental

In this study the multi-scale pore structure is characterized by X-ray microtomography (resolutions 1µm/2.5µm) and low voltage FIB-nanotomography (resolution 15 nm). Based on modern image analyses techniques, the 3D pore structure is described quantitatively. The influence of the permeability regarding the electrochemical performance can be characterized by impedance spectroscopy. In order to correlate the data sets from different microscopy methods with the electrochemical performance, new concepts for multi-scale characterisation have to be established.

Results

As shown in figure 1, the asbestos diaphragm can be considered as a 3-phase material consisting of macro-pores, dense-solid material and a nano-porous phase with reduced permeability. Whereas the solid phase can be distinguished from the permeable material with micro-CT on a lager scale, the details between macro-pores and the nano-porous phase require high resolution FIB-tomography. New concepts for multi-scale analyses and their correlation with electrochemical measurements are presented in this paper. Effects of pore structure (connectivity, percolation, tortuosity and constrictivity) will be discussed.

Fig. 1: 2d-images from tomography stacks by micro-CT (left) and FIB (right).

Corresponding author: Daniel Wiedenmann: [email protected], Tel. (+41) (44) 823 4860


67

STRUCTURAL AND THERMODYNAMICAL PROPERTIES OF DOUBLE-ANION COMPLEX HYDRIDE, Mg(BH4)(NH2)

Kazutoshi Miwa,1 Tatsuo Noritake,1 Masakazu Aoki,1 Mitsuru Matsumoto,1 Shin-ichi Towata,1 Hai-Wen Li,2 and Shin-ichi Orimo2

1 Toyota Central R&D Labs., Inc., Nagakute, Aichi 480-1192, Japan 2 Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan

The double-anion complex hydride, Mg(BH4)(NH2), has been synthesized by heating the mixture of Mg(BH4)2 and Mg(NH2)2 with the molar ratio of 1:1 up to 180°C. The x-ray diffraction (XRD) analysis reveals that the structure of Mg(BH4)(NH2) is tetragonal with the lattice constants of a = 5.771 Ǻ and c = 20.553 Ǻ. Using these experimental information, we have constructed model structures and performed the first-principles calculations for them. The symmetry is expected to be I41 (No. 80): The calculated lattice constants agree well with the experimental ones and the structure fairly reproduces the measured XRD pattern. Unfortunately, the hydrogen desorption reaction of Mg(BH4)(NH2) is predicted to be exothermic. In a practical point of view, it is necessary to stabilize the material for reversible hydrogen storage applications.

Introduction

The double-anion complex hydride, Mg(BH4)(NH2), has been synthesized. The starting material for sample preparation is a pre-milled mixture of Mg(BH4)2 and Mg(NH2)2 in a 1:1 molar ratio. The crystalline Mg(BH4)(NH2) can be obtained with heat treatment at 155-180°C. The x-ray diffraction (XRD) analysis indicates that the structure is tetragonal with the lattice constants of a = 5.771 Ǻ and c = 20.553 Ǻ. However, the detailed crystal structure is still uncertain. In this study, the first-principles calculations are performed to predict the structural and thermodynamical properties of Mg(BH4)(NH2).

Method

Our calculation is based on density functional theory within the ultrasoft pseudopotential method. Assuming the symmetry of crystal, the arrangement of cations and anions is determined roughly, and then the detailed structural parameters are optimized by the first-principles calculations.

Results

The model structure with space group I41 (No. 80) gives a satisfactory result. The calculated lattice constants are a = 5.778 Ǻ and c = 20.726 Ǻ which agree well with the experimental ones. This structure also reproduces the measured XRD pattern. The enthalpy change for the following mixing reaction is obtained to be H = -10 kJ/mol,

1/2Mg(BH4)2 + 1/2Mg(NH2) → Mg(BH4)(NH2).

This supports the formation of the double-anion system. The hydrogen release of Mg(BH4)(NH2) proceeds along the following reaction,

Mg(BH4)(NH2) → MgH2 + BN + 2H2.

This reaction is predicted to be exothermic with H = -7 kJ/mol H2, indicating that the reaction is not reversible. In a practical point of view, it is necessary to improve the reaction thermodynamics.

Corresponding author: Kazutoshi Miwa, email: [email protected]


68

A COMPARATIVE STUDY OF POROUS HYDROGEN STORAGE MATERIALS

Allan Walton, Steve Tedds, David Book, School of Metallurgy and Materials, University of Birmingham, Birmingham, UK The hydrogen sorption behaviour of a range of porous materials have been assessed using a gravimetric balance over a wide range of temperatures (77-293 K). The porous materials assessed include: zeolites; porous carbons; metal organic frameworks (MOFs); and Polymers of Intrinsic Microporosity (PIMs). The structural characteristics of these materials have been investigated using both volumetric and gravimetric techniques to assess the pore structure, density and surface area. PCT curves were used to calculate the heats of adsorption vs hydrogen uptake, and to monitor the temperature dependence of hydrogen capacity. Introduction

Porous materials have demonstrated high H2 capacities (up to 7.5 excess wt% at 77 K at 70bar) [1]. The maximum hydrogen uptake has been shown to be linearly related to specific surface area (SSA). However, at lower pressures, the temperature dependent hydrogen capacities have been shown to be related to the strength of the adsorbate – absorbent interactions, i.e. the isosteric heat of adsorption. In this work, these heats have been calculated for a range of materials using multiple pressure composition isotherms measured over a wide range of temperatures. The heats of adsorption are related to the pore size for each type of material. Experimental Variable temperature hydrogen isotherms were recorded on a Pressure Controlled Gravimetric Balance (Hiden IGA 001) up to 1.6 MPa. A pumped liquid nitrogen cryostat was used to control temperatures from 87-300 K, stable to ±0.1 K. Wt% H2 values were calculated as: the mass of H2 / dry mass of the sample. Results All of the materials exhibited a Type 1 adsorption isotherm. Although IRMOF-1 exhibited the highest uptake at 1.6 MPa (3.8 wt% at 87 K), at 0.1 MPa all of the other porous materials exhibited higher capacities. The heats of adsorption for all materials were calculated versus fractional coverage using

the Toth and Langmuir-Freundlich fits in conjunction with the Clausius-Clapeyron equation as well using a Virial method. At 50% fractional coverage the heats of adsorption for most of the materials was around 4 kJ mol-1H2. However, at lower fractional coverages the heats of adsorption differed significantly, with the activated carbon giving the highest values. Conclusion The heats of adsorption for each material did appear to correlate with pore size. Generally, the materials with a small pore size demonstrated a steeper hydrogen uptake at low pressure. However at 0.1 MPa the wt% H2 did not directly correlate with the heat of adsorption, which would indicate that surface area is likely to have an increased influence in this pressure range. A comparison is made between the surface area, pore size and heat of adsorption with reference to the ‘usable’ hydrogen storage capacity (in a vehicular store) at different temperatures. [1] M.K. Thomas; Dalton Trans., 2009,p1487 - 1505

Corresponding author: Allan Walton, email: [email protected], Tel. (+44) 121 414 3960

0

0.5

1

1.5

2

2.5

77 87 97 107 117 127 137Temp (K)

wt%

Hyd

roge

n

IRMOF-1

Cu-BTC

Zeolite NaX

Activated carbon

Wt% H2 vs Temperature at 0.1 MPa


73

ANALYSIS OF THERMAL DECOMPOSITION OF T-BUTYLAMINE BORANE Jordan Feigerle, Norm Smyrl, Jonathan Morrell, Ashley C. Stowe

B&W Y-12 National Security Complex, 301 Bear Creek Road, MS 8097, Oak Ridge, TN 37831 USA Amine boranes are a class of hydrogen storage materials which release significant yields of hydrogen gas upon heating to temperatures relevant for automotive applications. The thermodynamic stability of this class of amine boranes is correlated with the extensive di-hydrogen bonding between hydrides bound to boron and amine protons. Further, the hydrogen evolution follows a bimolecular pathway via the di-hydrogen bonding network. The thermal decomposition of t-butylamine borane (tBuAB), (CH3)3CH2NBH3, has been studied in order to understand the reaction pathway of hydrogen sorption and the impact of the t-butyl substitution dehydrogenation thermodynamics. 1H, 11B, and 13C solid state nuclear magnetic resonance (NMR) spectroscopy has revealed that heating initiates two separate reaction pathways: isomerization and hydrocarbon abstraction resulting in varying yields of isobutane and hydrogen. It is also possible that tBuAB dissociates about the N-B bond giving rise to borane stretching modes in the gas FTIR. Trapped t-butylamine (tBuA) which slowly diffuses from the tBuAB solid in 13C NMR studies appears to be present; however, this spectral region is convoluted by other decomposition products. 11B NMR indicates that the major reaction pathway results in hydrogen evolution with isobutane formation being present in smaller yields. The t-butyl substitution lowers the thermodynamic stability—compared to NH3BH3—but results in impure hydrogen gas stream and lowered capacity due to isobutene evolution. Introduction

Amine boranes release significant yields of hydrogen gas with heating; however, there are still significant challenges in rehydriding the spent fuel. The boron nitride oligomeric products are thermodynamically stable with respect to the hydrided fuel such that digestion and chemical processing is being considered. Investigation of substituted amine boranes can potential reveal subtly in the decomposition pathways that may help control the eventual decomposition products allowing for less energy intensive rehydrogenation. Further, it was shown that CBN species were less thermodynamically stable than BN analogues [1].

Results 1H, 13C, and 11B solid state MAS NMR studies of t-butylamine borane (tBuAB) heated isothermally to 80-95 oC over 10 hr evolved hydrogen and isobutane through a complex reaction pathway. A minor amount

of dissociation was also observed in evolved gas FTIR studies. Trapped t-butylamine gas was observed in the 13C solid state NMR spectrum. This was due to slow diffusion through the decomposing tBuAB lattice. Evolution of hydrogen gas dominates the decomposition. As the reaction proceeds, both [BNH]x—from initial isobutane release—and [CBNH]x oligomers are observed. Although the hydrogen yield is reduced by isobutane evolution, the [CBNH]x products are more thermoneutral and thus more easily regenerated. Perhaps the addition of substituted amine boranes as a mixture with ammonia borane will yield a material with sufficient H2 yields which results in a more thermoneutral [CBNH]x product.

References [1] D. J. Grant, M. H. Matus, K. D. Anderson, D. M. Camaioni, S. R. Neufeldt, C. F. Lane, D. A. Dixon, J. Phys. Chem. A 2009, 113, 6121–6132.

Corresponding author: Ashley Stowe, email: [email protected], Tel. (+1) (865) 241 0675


70

DESTABILIZATION REACTION OF LiBH4 + MH COMPOSITES ENHANCED BY HYDROGEN BACK PRESSRURE

Jae-Hyeok Shim,1 Jae-Hag Lim,1 Sami-ullah Rather,1 Young-Su Lee,1 Daniel Reed,2 Yoonyoung Kim,1 David Book,2 Young Whan Cho1 1Advanced Functional Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea 2School of Metallurgy and Materials, University of Birmingham, Birmingham B15 2TT, U.K.

Hydrogen back pressure remarkably promotes the formation of metal boride during the dehydrogenation of 4LiBH4 + YH3, 6LiBH4 + CeH2 and 6LiBH4 + CaH2 composites, which seems to be a general phenomenon in LiBH4-based reactive hydride composites that enables mutual destabilization between LiBH4 and metal hydride. The formation of metal boride plays a crucial role in the reversible hydrogen storage properties of these composites. The dependence of the dehydrogenation behavior on hydrogen back pressure might be associated with the microstructural evolution of the dehydrogenation products formed by a solid-liquid reaction.

Introduction

In this study, we investigate the effect of hydrogen back pressure on the dehydrogenation path of 4LiBH4 + YH3, 6LiBH4 + CeH2 and 6LiBH4 + CaH2 composites. Also, the reversibility of the dehydrogenation and rehydrogenation reactions of these composites is investigated.

Experimental

6LiBH4 + CaH2, 4LiBH4 + YH3, 6LiBH4 + CeH2 composites were prepared by ball milling. The dehydrogenation was conducted at 350 oC for 24 hours at two different initial pressures, vacuum and 3 bar of hydrogen. The rehydrogenation was done for 24 hours at 90 bar of hydrogen. XRD analysis was carried out on the ball-milled, dehydrogenated and rehydrogenated samples. Raman spectroscopy was performed on the dehydrogenated samples at room temperature.

Results

The dehydrogenation profiles of the 4LiBH4 + YH3 and 6LiBH4 + CeH2 composites at 350 oC are shown in Fig. 1. Although dehydrogenation of the 4LiBH4 + YH3

composite starting from vacuum presents fast kinetics up to about 1 hour, the dehydrogenation rate becomes slow after about 1 hour. The amount of hydrogen released after 24 hours is less than 2 wt%. On the other hand, this composite releases about 7.2 wt% hydrogen after 24 hours, when the dehydrogenation starts with a 3 bar hydrogen back pressure. The 6LiBH4 + CeH2 composite exhibits dehydrogenation behavior similar to that of the 4LiBH4 + YH3 composite, in terms of the effect of the initial pressure conditions. This positive effect of hydrogen back pressure during dehydrogenation is unexpected, considering that hydrogen back pressure would retard the decomposition of metal hydrides in a thermodynamic sense.

Fig. 1. Dehydrogenation profiles of the 4LiBH4 + YH3 composite under (a) static vacuum and (b) hydrogen back pressure and those of the 6LiBH4 + CeH2 composite under (c) static vacuum and (d) hydrogen back pressure.

Corresponding author: Jae-Hyeok Shim, email: [email protected], Tel. +82-2-958-6760


71

EFFECT OF NANOSTRUCTURING ON THE HYDROGEN STORAGE PROPERTIES OF LaNi5 SYSTEMS Benedetto Schiavo1,2, Boby Joseph3, Giacomo D’Alì Staiti1,2, Naurang L. Saini3 1Dip. di Fisica e Tecnologie Relative (DIFTER), Università di Palermo, Italy 2Istituto Tecnologie Avanzate, SS 113, Base di ASI ‘‘L. Broglio” ,Trapani, Italy 3Dip. di Fisica, Università di Roma “La Sapienza”, P.le Aldo Moro 2, Rome, 00185 Italy

Pressure–composition isotherms of LaNi5 alloys were studied as function of ball-milling time. Results indicate a strong hindrance to the hydrogenation of the long-time ball-milled samples. Local structural studies reveal that the nanostructured powders are characterised by reduced unit cell volume and enhanced atomic disorder. Results of the x-ray diffraction and differential scanning calorimetry are in agreement with the results of the local structure studies.

Introduction

Nanostructuring using ball-milling is found to be very effective in improving the hydrogen sorption kinetics of materials like Mg [1]. However, ball-milling induced nanostructuring is found to have an adverse effect on the hydrogen sorption properties of the conventional hydrogen storage material, LaNi5 [2]. We have studied the above system using a number of experimental techniques -a brief summary of the results are presented.

Experimental

Ball-milling of the LaNi5 powders, with varying milling times, were performed using a Fritsch miller. Some of the milled samples were annealed under high vacuum. Hydrogen sorption properties of these samples were studied by measuring the pressure-composition isotherms (PCIs) at 35°C using an automated Sievert’s equipment. Local structure of these samples were studied using the Ni K-edge extended x-ray absorption fine structure (EXAFS). Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) were also utilised for the characterization of the samples.

Results

With increase in milling time, PCIs showed an increased in the plateau-pressure and a reduction in the hydrogen capacity at pressures below 20 bar [2]. DSC

measurements indicated an increase in the defect density with milling time. Observed enhancement in H2 intake in the initial part of the PCIs can be explained considering the milling induced particle size reduction and increase in surface defects. XRD results reveal that the long-time milled samples have identical crystal phase as that of the un-milled, but with slightly reduced lattice parameters and drastically reduced average crystallite sizes [3]. EXAFS results revealed a reduction in the near-neighbour (NN) distances in the long time ball-milled samples. In addition, a large increase in the atomic disorder was evident (as seen from the large mean square relative displacements (MSRDs) of the NN distances) [4]. Interestingly, in the long-time ball-milled samples, annealing is found to be have little effects in bringing back the atomic order [4]. Decrease in the NN distances and the corresponding increase in the MSRDs may be causing a higher energy barrier for the hydride phase formation in the long time milled powders.

References [1] A. Zaluska et al., J. Alloys Compd 288 (1999) 217 [2] B. Joseph, B. Schiavo, J. Alloys Compd 480 (2009)

912 [3] B. Joseph, B. Schiavo et al., Proc. of HYSDAYS-

2009, Torino, Italy [4] B. Joseph, A. Iadecola, B. Schiavo et al., J. Solid

State Chem. (submitted)

Corresponding author: B. Schiavo, email: [email protected], Tel. (+39) 0923 550130


76

POROSITY GRADED ZrO2 DIAPHRAGMS FOR ALKALINE ELECTROLYSIS

M. Gorbar 1,2, D. Wiedenmann 1,2, V.P. Zakaznova-Herzog 1, U.F. Vogt 1, B. Grobety 2, A. Züttel 1 1Empa Materials Science and Technology, Dept. Energy, Environment & Mobility, Sec. Hydrogen & Energy, CH-8600 Dübendorf, Switzerland 2University of Fribourg, Dept. of Geosciences, Chemin du Musée 6, Pérolles, CH-1700, Fribourg, Switzerland The investigation and characterization of metal oxide based ceramic materials is essential for the quest to find materials to replace the chrysotile asbestos diaphragm used in today’s alkaline electrolyses. As a suitable material with high chemical stability to KOH 3-mol%-Y2O3-doped tetragonal-ZrO2 powder was chosen. Initial tests were performed using a lab electrolyser cell with Ni wire mesh electrodes of 34 mm diameter. Test focus was the ion conductivity, gas purity as well as chemical and mechanical stability.

Introduction

There is an increasing interest in hydrogen as an energy carrier. A well-established method of producing high purity hydrogen from water is the alkaline electrolysis. Such zero-gap electrolysers operate at 85°C, 32 bars and use a 25 wt% KOH solution. In these electrolysers the asbestos diaphragm prevents the mixing of hydrogen and oxygen, while warranting sufficient ion conductivity. Although long-term studies have shown that chrysotile asbestos is stable in KOH at temperature below 100°C, higher temperatures will cause the diaphragm to dissolve. Due to these limiting factors and the ban on use of asbestos in many countries a replacement for asbestos is crucial for the continuation of this technology.

Experimental part

To produce replacement diaphragms graded porous substrates of ZrO2 have been prepared. Mixtures of 3-mol% Y2O3-doped tetragonal ZrO2 powder (TZ-3Y) and carbon as pore formers were uniaxialy pressed at 50 kN to a cylindrical preform (d = 50 mm, 2.5 mm thickness) and subsequently sintered at 1200°C for 1 hour. Careful attention was given to keep the

pore size of the TZ-3Y diaphragms samples below the diameter of the hydrogen bubbles evolving during electrolysis [1]. The Diaphragms were tested using the lab-electrolytic cell setup with a current density of 200 mA/cm2 and ambient conditions. This work provides the basis for the development of new diaphragms with improved mechanical stability, better cell performance and better electric power efficiency.

Results

By using different amounts of carbon as a pore former (10, 20 and 30 vol%, respectively) the effect on the open porosity was examinant. Carbon powder and fibres where used, allowing for spherical and fibrillose pore structure after carbon burn out. This method for making ceramic bodies having a graded porosity improved ion conductivity and so reduced the cell voltage drop. A slight decline in the hydrogen purity was noted. All results were recorded and compared to initial tests done using chrysotile-asbestos as a diaphragm. [1] E. Barendrecht et al., The Effect of Gas Bubble Evolution on the Energy Efficiency in Water Electrolysis. Annual Report 1983, Technische Hogeschool Eindhoven.

Corresponding author: Michal Gorbar, email: [email protected] , Tel. (+41) (44) 823 4301


73

POSTERS

SESSION 2

TUESDAY


74

HYDROGEN-POWERED APU FOR MOBILE RAIL CATERING SERVICE: THE IHPOS-E PROJECT M. Bielmann1, M. Hachen2, A. Züttel1 1EMPA Materials Science and Technology, Dept. Energy, Environment & Mobility, Sec. Hydrogen & Energy, CH-8600 Dübendorf, Switzerland 2 Berne University of Applied Sciences, Department Energysystems, 2501 Biel/Bienne

Energy concept

Hydrogen as a high density energy carrier is developing in niche markets as a viable economical alternative to other sources of off-grid energy supply. In these markets, they directly compete with batteries as a benchmark solution. While hydrogen can hardly compete in applications where low energy capacity is needed, in domains with high energy capacity the technology starts to be competitive.

The main advantages of hydrogen as source of energy in an APU system are:

Scalable energy content

No output dependence on "state of charge"

Higher volumetric energy storage density

These advantages are explored the project IPHOS.

Application

Elvetino is the catering company of the Swiss Railway. As a speciality, they provide quality espresso coffee in a mobile sales unit directly at the seat of the passengers. Currently, the units are powered by Li-Ion Batteries. While on low-traffic connections this solution is viable, on high-volume connections the solution proved not sufficient and not flexible to the needs of the company. The company CEKA, specialized in just-in-time production of electrical tools decided to solve the problem by a fuel cell unit offering the same service but a flexible energy content with no restrictions regarding charging times. The

unit is based on a metal-hydride hydrogen storage offering low pressure hydrogen storage with safety benefits compared to pressurized hydrogen.

Outlook

The current solution is based on an air-cooled fuel cell. The implementation of a water-cooled fuel cell can offer significant energy and space savings through water preheating and more efficient waste-heat management. It reduces the complexity of the integration of metal hydride energy storage as a source of hydrogen, where high kinetics are demanded and hard to satisfy because of limited heat transfer to the tank. Water heating can be implemented by catalytical combustion of hydrogen, reducing the necessary electrical output of the fuel cell further. While synergies for other APU-applications must be sacrificed for energy efficiency, such a solution can potentially be far superior to a battery based solution in this particular application.

Corresponding author: Michael Bielmann, email: [email protected]


75

STUDY OF HYDROGEN CONTENT AND DEPTH PROFILE IN MAGNESIUM AND MAGNESIUM ALLUMINIUM FILMS BY ERDA

Pragya Jaina, Ankur Jaina, Devendra Vyasa, S.A.Khanb, I.P.Jaina* a Centre for Non-Conventional Energy Resources, University of Rajasthan, Jaipur-302055, India b Inter University Accelerator Centre, Aruna Asif Ali Marg, New Delhi 110 067, India

Pd/Mg/Pd and Pd/Al/Mg/Pd multilayered films were deposited on Si/glass substrate using vapour deposition technique. Pd was deposited on both sides to ensure a fast dissociation rate and good transport properties of hydrogen and to avoid oxidation of Mg from both surface and substrate side. The particle size and roughness is estimated in nano-meter range by AFM studies. The nano structured films have been hydrogenated at 230oC and 5 bar H2 pressure for 2hrs. The morphological and structural changes have been investigated by AFM and GIXRD. Hydrogen content and depth profile is measurement by Elastic Recoil Detection Analysis using 100MeV Ag ion beam.

Introduction

Thin film technique provides powerful way to investigate the interaction between nano-scaled Mg and H because the composition, interface and crystallinity of thin film can be easily controlled on nano scale [1]. Thus, various attempts have been undertaken to study the hydrogen storage properties of Mg thin films [2]. The present work reports hydrogen content and depth profiling of Pd capped Mg and Mg/Al thin films.

Experimental

Mg (150nm) and Mg (100nm)/Al (50nm) films were prepared and capped by 20nm Pd from both sides on Si/ glass substrate using vapor deposition technique at 10-6 torr vacuum. The phase identification and modifications due to hydrogen have been made by GIXRD and AFM techniques. Hydrogen content measurements were done by ERDA using 100 MeV Ag ion beam irradiation.

Results

XRD patterns of as-prepared Pd/Mg/Pd and Pd/Al/Mg/Pd films indicate Mg [002], Pd [111] and Pd [200] as the preferential growth orientation in both samples with an additional peak of Al [111] in Mg-Al system. Randomly oriented hexagonal platelets of Mg

crystal found in AFM images confirm the XRD findings.

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Pd/Mg/Pd and Pd/Al/Mg/Pd thin films.

On hydrogenation of Mg thin film, MgH2 [110] peak appears indicating the formation of magnesium hydride. Although small amount of Palladium hydride phase with orientation [200] is visible, but still considerable amount of Pd was found to be unreacted as like as other studies done on similar systems [3]. In case of Mg-Al system a peak of AlH3 [100] is observed along with MgH2 peak.

References [1] R. Domenech-Ferrer, M. Gurusamy Sridharan,

G. Garcia, F. Pi, J. Rodriguez-Viejo, J. Power Sources 169 (2007) 117–122.

[2] J. Paillier, S. Bouhtiyya, G.G. Ross, L. Roue, Thin Solid Films 500 (2006) 117–123.

[3] Sanjiv Kumar, G.L.N. Reddy, V.S.Raju, J. Alloys Compd. 476 (2009) 500-506

Corresponding author: I.P.Jain*, email: [email protected], Tel. (+91) (141) 2711049


76

NMR STUDIES ON Li2(BH4)(NH2) AND Li4(BH4)(NH2)3

Pascal Martelliº¹, Arndt Remhofº, Matthias Ernst², Motoaki Matsuo³, Shin-ichi Orimo³, Andreas Züttelº¹ º EMPA Materials Science and Technology, Dept. Energy, Environment & Mobility, Abt. 138 “Hydrogen & Energy”, Überlandstrasse 129, 8600 Dübendorf, Switzerland ¹University of Fribourg, Physics departement, Ch. du Musée 3, 1700 Fribourg, Switzerland ²ETH Zürich, Physical Chemistry, Wolfgang-Pauli-Strasse 10, 8093 Zürich, Switzerland ³Institute for Materials Research, Tohoku University, Katahira 2-1-1, Sendai, 980-8577, Japan Complex hydrides with (BH4)

- and (NH2)- anions are recently discussed as a new lithium fast-ion conductors with

conductivites in the order of 10-3 S cm-1 at room temperature[1] which is comparable with Nafion[2]. We used 7Li nuclear magnetic resonance (NMR) spectroscopy to measure the Li mobility within LiBH4, Li2(BH4)(NH2) and Li4(BH4)(NH2)3. In pure LiBH4 the phase transition is accompanied by a sudden sharpening of the signal. We attribute this effect to a motional narrowing due to the increased Li mobility within the high temperature phase. Similar Li mobilities are observed in Li2(BH4)(NH2) and Li4(BH4)(NH2)3 even at room temperature.

Introduction Research on lithium ion conductors is significantly important because they may potentially be applied to solid electrolytes to improve safety and energy-density related issues of conventional lithium-ion batteries. [1]

Experimental The NMR measurements, were carried out at ETH Zürich, using a Bruker Cryomagnet BZH 400/89 with an applied magnetic field of 9.4 T, and a frequency of 155.5 MHz. LiBH4 was provided by Sigma Aldrich, Li2(BH4)(NH2) and Li4(BH4)(NH2)3 were prepared at Tohoku University.

Results

Fig. 1: 7Li (I=3/2) NMR spectra of LiBH4 at low and high temperature phase.

Figures 1 and 2 show the respective 7Li and Li2(BH4)(NH2), Li4(BH4)(NH2)3 NMR spectra.

The phase transition in LiBH4 is accompanied by a sudden sharpening of the signal. Thereby the FWHM decreases from 12.7 Hz at RT to 0.6 Hz at 150°C by more than one order of magnitude. We attribute this effect to the increased diffusivity of Li through the lattice. This effect, known as “motional narrowing”, can be observed for Li2(BH4)(NH2) and Li4(BH4)(NH2)3. at much lower temperatures as displayed in fig.2. Fig. 2: 7Li (I=3/2) NMR spectra of Li2(BH4)(NH2) and Li4(BH4)(NH2)3 measured at selected temperature below their thermal decomposition.

References [1] Matsuo, M., Remhof, A., Martelli, P., Zuettel,

A., JACS 131, 16389 (2009). [2] J. Electrochem. Soc., 149, (12), 1556 (2002)

Corresponding author: Pascal Martelli, email: [email protected], Tel. (+41) (44) 823 4746


77

THERMODYNAMIC PROPERTIES OF LH3/AlF3 AND MgH2/MgF2 SYSTEMS AS HYDROGEN STORAGE MATERIALS: A COMPUTATIONAL APPROACH

Marta Corno, Piero Ugliengo, Marcello Baricco

Dipartimento di Chimica IFM, NIS Centre of Excellence and INSTM, University of Torino, Via P. Giuria 7/9, 10125, Torino, Italy.

Thermodynamic properties of aluminium and magnesium hydrides and fluorides, both pure and mixed, have been computed by ab initio calculations. The DFT method with the pure GGA Hamiltonian PBE has been applied and the reference code used is CRYSTAL06 with localised Gaussian basis set. An important stage of the study has been the calibration of computational parameters, specifically for Hamiltonian and basis set. Solid solutions have been modelled and characterised by means of structural, electronic, vibrational and thermodynamic properties.

Introduction

In this work ab initio calculations on AlH3/AlF3 and MgH2/MgF2 are presented. In particular, the full characterisation of computed structural, electronic, vibrational and thermo-dynamic properties has been carried out both on pure compounds and on solid solutions. Several significant reactions have been simulated, such as formation, fluorination and dehydrogenation.

Experimental

The Density Functional Theory has been chosen, considering different Hamiltonians, from pure GGA (PBE) to hybrid (B3LYP), within the periodic CRYSTAL06 code. [1] The calibration of the computational strategy has regarded also the optimization of the basis set, ranging from polarized double- to quadruple-zeta cases.

Results

We optimised the computational strategy for the simulation of hydrides and fluorides of light-metals, showing how different choices of

computational parameters could affect the characterised properties.

+ →

+

Fig. 1 Fluorination reaction of aluminium hydride.

Different configurations for solid solutions have been studied, using a newly implemented algorithm in the CRYSTAL code, which allows the classification by symmetry for each H/F ratio. The computed thermodynamic values have shown a fair agreement both with experimental and thermodynamical calculations. These data are relevant to improve our understanding of solid solutions for which only scarce experimental data are available. This work is part of the European FP7 Project FLYHY “Fluorine Substituted High Capacity Hydrides for Hydrogen Storage at low Working Temperatures”. [2]

References [1] www.crystal.unito.it [2] www.flyhy.eu

Corresponding author: Marta Corno, email: [email protected], Tel. (+39) (011) 670 4597


78

R&D STATUS ON HYDROGEN PRODUCTION, STORAGE, AND UTILIZATION TECHNOLOGIES IN KOREA

Moon-Sun Chung, Jong-Won Kim

Hydrogen Energy R&D Centre, Korea Institute of Energy Research, Daejeon, Republic of Korea

In October 2003, Korean government launched Hydrogen Energy R&D Center (HERC) as a member of the 21st Century Frontier R&D programs supported by the MEST. The HERC has conducted research on the key technologies for the production, storage, and utilization of hydrogen energy for expediting realization of hydrogen economy based on renewable energy sources. The main purposes of this article are to overview the current status of research programs conducted by Hydrogen Energy R&D Center based on the present topics and to introduce achievements in each research program as well as the future works in Korea.

R&D Issues on Hydrogen Energy

Production of hydrogen from biomass may be achieved by biological fermentation or photosynthesis process [1, 2]. In addition, photochemical hydrogen production as well as low or high temperature water electrolysis is one of the final goals to achieve though it is not show any marked economy of scale at the present [3]. There are three main hydrogen storage methods including high compression, chemical hydride and hydrogen storage materials. We have already demonstrated the highly pressurized hydrogen system on fuel cell vehicles with Hyundai motor company. The nano-structured hydrogen storage materials have some advantages such as high volumetric storage capacity, little energy loss, and highest safety [4, 5]. However, they still have low specific storage capacity and poor cyclic properties. We also try to develop a hydrogen storage system using chemical hydride like NaBH4. Finally, hydrogen can be used as a fuel in the conventional internal combustion engines as well as in the fuel cells. Further, if there is no transformation of linear momentum for reciprocal motion into angular momentum for circular motion than mechanical loss can be reduced. Additionally, the manufacturing cost of internal combustion engine is relatively low in comparison with that of fuel cells. For these reasons, a linear piston engine with generation system using hydrogen is a

promising technology to obtain electricity from hydrogen combustion directly [6].

Roadmap for Hydrogen Energy R&D in Korea.

References [1] M.-S. Chung et al; 2007 Asian Bio-Hydrogen

Symposium (2007) [2] M.-S. Kim, et al; Int. J. Hydrogen Energy, 31

(2006) 812-816 [3] J.-O. Baeg,et al; Advanced Fuctional Materials,

16 (2006) 1349-1354 [4] Y.-W. Cho, et al; Catalysis Today, 120 (2007)

292-297 [5] J.-H. Kim, et al; Angew. Chem. Int. Ed. 46

(2007) 8230-8233 [6] D.-H. Cho, “Mover stabilization device of linear

motor and generator”, Korea Patent 20-038698

Corresponding author: Dr. Moon-Sun Chung, email: [email protected], Tel. (+82) (42) 860 3591


79

IMPROVEMENT OF DECOMPOSITION PROPERTIES OF LiBH4 DISPERSED ON MODIFIED MULTI-WALLED CARBON NANOTUBES

Filippo Agresti1, Ashish Khandelwal1, Giovanni Capurso1, Sergio Lo Russo2, Amedeo Maddalena1, Giovanni Principi1 1Università di Padova, Dipartimento di Ingegneria Meccanica,Settore Materiali, via Marzolo 9, 35131, Padova, Italy. 2Università di Padova, Dipartimento di Fisica and CNISM, via Marzolo 8, 35131, Padova, Italy

The decomposition properties of LiBH4 dispersed on multi-walled carbon nano-tubes (MWCNT) have been studied. Commercial MWCNT were ball milled for different times in order to increase the specific surface area (SSA). Thermal programmed desorption measurements (TPD) have been performed on samples with different SSA of MWCNT and different LiBH4 to MWCNT ratio. Pressure composition isotherms (PCI) have been obtained at different temperatures in order to estimate the ΔH and ΔS of decomposition. It has been observed that the dispersion of LiBH4 on MWCNT leads to lower decomposition temperature compared to pure LiBH4. Moreover, the decomposition temperature further decreases with increasing MWCNT surface area. An interpretation of the kinetic effect is given in the work.

Introduction

LiBH4 is one of the most studied complex hydride for hydrogen storage, due to its high theoretical gravimetric hydrogen capacity (18.4 wt%). The research is addressed to reduce the decomposition temperature (>400 °C) and to improve reversibility. In this work it is shown that LiBH4 deposited on MWCNT modified by ball milling exhibits lower decomposition temperature compared to the pure material.

Experimental

Commercial MWCNT have been modified by high energy ball milling in order to increase the SSA. Samples have been milled using a SPEX 8000M shaker mill with a ball to powder ratio of 10:1. LiBH4 has been deposited on the MWCNT by solvent infiltration technique using methyl tert-butyl ether (MTBE). Samples with different LiBH4:MWCNT mass ratios and samples with fixed composition but using MWCNT with different SSA have been prepared.

Results

LiBH4 dispersed on MWCNT shows decreased decomposition temperature with respect to pure material by more than 60

°C. The decomposition temperature of LiBH4 further decreases with increasing the SSA of MWCNT and the effect is proposed to be due to heterogeneous nucleation of decomposition products or intermediate phases on the carbon surface from liquid LiBH4.

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Finally, the dispersion of LiBH4 on the high surface area of MWCNT does not seem to lead to thermodynamic destabilization with respect to pure material due to size effect

Corresponding author: Filippo Agresti, email: [email protected] , Tel. (+39) 049 827 5828


80

HYDROGEN EVOLUTION FROM DECOMPOSITION OF BOROHYDRIDES: THE “BORON EFFECT”

F. Pendolino a, S. Garroni b, C. Milanese c, A. Girella c, A. Borgschulte a, D. Baro b, A. Marini c and A. Züttel a a Empa, Abt. 138 “Hydrogen & Energy”, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland b Department de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra, Spain c CSGI Dep. Physical Chemistry, University of Pavia, Viale Taramelli 16, I-27100 Pavia, Italy

The boron effect was investigated for the thermal decomposition of light metal borohydrides M(BH4)n (M = Li, Na, K, Ca). The addition of boron enhanced the dehydrogenation process via the formation of new intermediate. A partial decomposition of material was needed in order to form this intermediate. The decomposition temperature of lithium borohydride and calcium borohydride was lowered of 150 °C and 20 °C respectively.

Introduction

Hydrogen as a future energy carrier requires a technology to efficiently store it in a solid material which can release and recharge hydrogen as fast as possible at minimum energy loss [1]. The purpose of this work is to investigate of the “boron effect” on the dehydrogenation of alkali and alkaline earth metal borohydrides under hydrogen pressure in non-isothermal conditions (non-equilibrium).

Experimental

The boron mixtures M(BH4)n+B were prepared by mixing various molar ratios, X=moles M(BH4)n / moles amorphous B, in a mortar. The thermal decompositions were studied by means of differential scanning calorimetry (DSC), mass spectrometry and volumetric analysis in the mixture temperature range 25-600ºC.

Results

The addition of boron affected the dehydrogenation, changing the reaction path via a new intermediate. The formation of a new intermediate occurred after partial decomposition of the material. Positively, the boron effect decreased the Td for LiBH4 and Ca(BH4)2 of 150 °C and 20 °C respectively (Fig. 1, 2). On the other hand, the boron presence inhibited the thermal decomposition of NaBH4. The nature of new intermediate is the key to describe the mechanism of reaction, that is currently under investigation.

References [1] L. Schlapbach & A. Züttel Nature, p. 353, v.414

(2001) [2] F. Pendolino et al. Phys. Chem. C, p.17231,

v. 113 (2009)

Corresponding author: Flavio Pendolino, email: [email protected] Tel. (+41) (44) 823 4776

Figure 1: DSC traces for LiBH4 and LiBH4+B under 1bar H2 at 11 ºC/min.

Figure 2: DSC traces for Ca(BH4)2 and Ca(BH4)2 +B under 1bar H2 at 11 ºC/min


81

LITHIUM FAST-ION CONDUCTION IN LiBH4

Motoaki Matsuo and Shin-ichi Orimo

Institute for Materials Research, Tohoku University, 980-8577 Sendai, Japan

We have recently reported that LiBH4 exhibits lithium fast-ion conduction (more than 1×10−3 S/cm),[1] which was observed during attempts to clarify the microwave absorbing mechanism.[2] The lithium ion conductivity of LiBH4 jumps by three orders of magnitude due to its structural transition from orthorhombic to hexagonal (fast-ion conduction) phases at approximately 390 K. The fast-ion conduction phase can be stabilized by addition of lithium halides, resulting in the enhancement of the ion conductivity at room temperature(RT).[3-5]

Introduction

The lithium fast-ion conduction in LiBH4 could potentially aid the development of new solid electrolytes for lithium-ion secondary batteries. Therefore, research directions on LiBH4 are to stabilize the fast-ion conduction phase to least possible temperatures, and also to enhance the conductivity. In this work, we describe the effects of lithium halide (LiCl and LiI) addition to LiBH4 on the stability and the lithium ion conductivity.

Experimental

Approximately 500 mg mixtures of LiBH4 and LiCl or LiI were mechanically milled for 5 h under Ar. The lithium ion conductivity was determined by ac complex impedance method between 303 and 433 K. The samples were examined by ex- and in-situ powder X-ray diffraction measurements (XRD). Thermal analysis was carried out by differential scanning calorimetry (DSC).

Results

As shown in Figure 1, the LiCl addition lowered the transition temperature of LiBH4 by 30 K (380 → 350 K), indicating the stabilization of the lithium fast-ion conduction phase at lower temperature. Additionally, the ion conductivity in the orthorhombic phase was increased by one order of magnitude. In the case of LiI addition, on the other hand, the fast-ion

conduction phase was stabilized at RT, resulting in the high ion conductivity of 2×10-5 S/cm. These properties were found to be attributed to the dissolution of LiCl and LiI into LiBH4. Furthermore, just recently, complex hydrides with (BH4)

– and (NH2)

– anions, Li2(BH4)(NH2) and Li4(BH4)(NH2)3, were found to exhibit lithium fast-ion conductivity of 2×10−4 S/cm at RT.[6]

Fig. 1. Temperature dependences of the lithium ion conductivity of LiBH4 (black), LiBH4+0.33LiCl (blue) and LiBH4+0.33LiI (red).

References [1] Matsuo et al; Appl. Phys. Lett. 91 (2007) 224103 [2] Matsuo et al; Appl. Phys. Lett. 90 (2007) 232907 [3] Matsuo et al; Appl. Phys. Lett. 94 (2009) 084103 [4] Oguchi et al; Appl. Phys. Lett. 94 (2009) 141912 [5] Maekawa et al; J. Am. Chem. Soc. 131 (2009) 894 [6] Matsuo et al; J. Am. Chem. Soc. in press

Corresponding author: Shin-ichi Orimo, email: [email protected], Tel. (+88) (22) 215 2093


PROCEEDINGS 82

SCIENCE OF HYDROGEN & ENERGY AWARD

The “Science of Hydrogen & Energy” award is a price, just similar to the Nobel prize, for an extraordinary contribution to the sciences of hydrogen. The aim is to award a prize to a distinct scientist for his scientific work of a life time.

SCIENCE OF HYDROGEN & ENERGY AWARD 2007

Prof. Dr. Ronald Griessen

Ronald Pierre Griessen, was born March 7, 1945 in Switzerland. He received 1964 his Baccalauréat, from Gymnase français in Bienne, Switzerland. From 1964 – 1969 he studied Physics and Mathematics at the Swiss Federal Institute of Technology (ETH) in Zürich and finished with a Diploma-thesis on: "Magnetostriction of type-II superconductors". From 1969 – 1973 he was PhD student in the Low Temperature Physics Group of Prof.dr J.L. Olsen at the ETH. PhD-thesis on: "Oscillatory Magnetostriction and the stress dependence of the Fermi Surface of Al, In, Zn and Mg". From 1974 – 1976 he was Research Associate at the McLennan Physical Laboratory of the University of Toronto, Canada where he worked on the electronic structure of spin-density-wave systems and quantum oscillations.In 1976 he was visiting scientist at the ETH, Zürich and from 1976 – 1980 senior lecturer at the Vrije Universiteit in Amsterdam. Since 1980 he is Full Professor in charge of the Department of Condensed Matter Physics.

Ronald Griessen has investigated the thermodynamics of palladium films and the isotope effect on the electronic structure of hydrides. Furthermore, the effect of anharmonicity and Debye-Waller factor on superconductivity of PdHx and PdDx have been studied by Ronald before he developed a semi-empirical model for the heat of solution of hydrogen in transition metals. He also studied the trapping energy for hydrogen on lattice defects as well as the heat of solution of disordered transition metals. The volume expansion upon hydrogen absorption, the Gorsky-effect, the diffusion, electromigration and the hydrogen diffusion in magnetig fields are just a few other subjects treated and described by Ronald Griessen. Then Ronald decided to test the world of high pressure hydrogen and described the properties of hydrides formed at very high pressure as well as the properties of hydrogen gas in a wide temperature and pressure range. During the intense investigation of superconductors and metal hydrides under high hydrogen pressure in a diamond anvil cell, Ronald has discovered the switchable optical properties of yttrium and lanthanum hydride films. This has then stimulated Ronald to investigate thin films with optical methods and to develop new methods for the combinatorial search of new hydride phases as well as for the determination of the thermodynamic parameters e.g. stability and kinetics of the hydrides. Furthermore, new applications for hydrides as hydrogen detectors and optical filters have been developed in his group.


PROCEEDINGS 83


Prof. Dr. Louis Schlapbach

Louis Schlapbach, born March 4, 1944 in Belp Switzerland. He graduated from the Swiss Federal Institute of Technology Zurich (ETHZ) in Experimental Physics and got his PhD in Solid State Physics – Magnetism also at ETHZ. As a postdoc at a CNRS laboratory in Paris, he studied hydrogen storage in intermetallic compounds. Back at ETHZ, he developed the surface science aspects of the hydrogen interaction with metals and alloys. From 1988 till 2001, Louis Schlapbach was Full Professor for Physics at the University of Fribourg. As such he built up a research team of 20-25 people working on the topic „New Materials and their Surfaces“ resulting in about 40 PhD, 200 scientific papers and some patents. A strong collaboration with industry was established. In spring 2001, he has been appointed CEO of Empa, the materials science and technology institution of the ETH domain with 750 coworkers in Dübendorf, St. Gallen and Thun.

Louis Schlapbach started his scientific work in 1970, 38 years ago, with the investigation of the Hall effect, electrical transport and magnetic susceptibility of liquid rear earth elements like Cerium. 30 years ago in 1970 he was coauthor with Busch and Waldirich on a paper about the hydrides of La-Ni compounds. LaNi5 was subsequently investigated in view of the structure, surface segregations, hydrogen occupation of interstitial sites and as electrode material.LaNi5 is still the base material for most of the electrochemical applications of metal hydrides today. The work on LaNi5 was complemented by the research on FeTi. Louis Schlapbach realized the importance of the surface composition for the hydrogen sorption process and he was able to describe the role of the surface-active species. Furthermore, he investigated the changes of the surface composition of LaNi5 and FeTi in oxidizing atmospheres and he found the formation of metallic clusters as superparamagnetic particles acting as the active sites in hydrogen dissociation and recombination. The investigation of the surface of metal hydrides was further intensified by means of X-ray photoelectron spectroscopy. Louis Schlapbach was the first scientist correctly describing the activation process of a metal hydride and, furthermore, to model the chemical composition and states of the elements in a surface profile. He also succeeded to analyze the electronic structure of raere earth elements and their hydrides by means of photoemission spectroscopy. In 1990 Louis Schlapbach edited the two books "Hydrogen in Intermetallic Compounds I & II" of the Springer Sereies. The books became a very important reference for all the researchers active in the field of hydrides.


PROCEEDINGS 84


Dr. Gary Sandrock

Gary Sandrock received his master from the Institute of Technology, Cleveland in 1965 and his Ph.D. from the Western Reserve University, Cleveland in 1971. He worked from 1962-1969 as a research metallurgist in the NASA Lewis Research Center, Cleveland, Ohio. From 1971-1983 he was Section Manager of Energy Systems at Inco Research and Development Center, Suffern, NY. From 1983-1991 he was Vice President and Director of Technology at Ergenics, Inc., Ringwood, NJ. From 1992-1993 Gary Sandrock was visiting professor at the Kogakuin University, Hachioji, Tokyo, Japan where he developed a new chemical surface treatment and investigated the activation characteristics of chemical treated AB5 alloys. Gary then became the president of SunaTech, Inc., Ringwood, NJ, where he developed reversible hydrogen storage systems. At the same time Gary Operating Agent, International Energy Agency Hydrogen Implementing agreement Tasks 12 & 17 (Hydrogen Storage Materials) and worked as a consultant for the US DOE via Sandia National Laboratories, Livermore, CA.

In 1995 Gary Sandrock started to creat and mainten Hydride Databases of IEA(HIA)/DOE/SNL (http://hydpark.ca.sandia.gov) and he is author of several book chapters and review papers e.g. “A panoramic overview of hydrogen storage alloys from a gas reaction point of view”. His recent research concentrates on the catalysis of the hydrogen desorption from alanates and most recently Gary investigated the hydrogen desorption behavior of AlH3 and explaned the mechanism of the kinetic stabilisation of aluminumhydrid. Furthermore, he published a paper entitled “Accelerated thermal decomposition of AlH3 for hydrogen-fueled vehicles” where he shows the possible ways to change the activation barrier for the hydrogen desorption in a controlled way. Gary Sandrock not only made significant achevements in understanding metal hydrides he also built the bridge from sciences to application. Furthermore, his scientific review papers and the hydride database are inestimably value for the hydride society.


PROCEEDINGS 85


Prof. Dr. Jens Norskov

Jens Norskov was born on September 21 in 1952. He received his Master dgree in physics and chemistry from the University of Aarhus, Denmark in 1976 and his PhD in theoretical physics in 1979. During his PhD he published papers about the electronic structure of H and He in metal vacancies and the contraction of diatomic molecules upon chemisorption. Jens Norskov was a Post Doc at IBM in Yorktown Heights, New York in 1979 and was affiliated with Nordita, (Nordic Institute for Theoretical Physics) in Copenhagen before he became a member of the scientific staff of Haldor Topsøe A/S, Lyngby in 1981. He continued the investigation of gas molecules at the surface of metals and developed a picture of adsorption and desorption of hydrogen emerging from self-consistent model calculations. In 1992 he was appointed as a professor of theoretical physics in the department of physics at the Technical University of Denmark, Lyngby and became the director of the Center for Atomic-scale Materials Physics (CAMP), Department of Physics, Technical University of Denmark, Lyngby.

Recent research of the group of Jens Norskov covers several of the most relevant topics: 1) The development of theoretical methods e.g. “Scaling Properties of Adsorption Energies for Hydrogen-Containing Molecules on Transition-Metal Surfaces”; 2) Theoretical surface science e.g. “Role of strain and ligand effects in the modification of the electronic and chemical properties of bimetallic surfaces”; 3) Nanostructures and materials properties e.g. Atomic-scale imaging of carbon nanofiber growth”; 4) Heterogeneous catalysis e.g. “Ammonia synthesis from first principles calculations”; 5) Biomolecules e.g. “Biomimetic hydrogen evolution”; 6) Electrochemistry and fuel cells e.g. “The origin of the overpotential for oxygen reduction at a fuel cell cathode”; 7) Hydrogen storage e.g. “Metal ammine complexes for hydrogen storage” Jens Norskov is not only a creative and brilliant scientist, he also belongs to the few scientist able to successfully combine theoretical approches with experimental observations for the understanding of the basic phenomena. It is always a great pleasure to listen to Jens Norskovs talks, which are exciting eye opening stories combined with some great new stimulating ideas.


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Prof. Dr. Rüdiger Bormann

Rüdiger Bormann was born September, 14 1952 in Germany. He received 1977 his diploma in physics (Metalphysics), from the University Göttingen and 1979 his Dr. rer. nat. from the University Göttingen. From 1981 to 1982 he was visiting scientist in the Dept. of Applied Physics at Stanford University, U.S.A. From 1982 to 1988 he was Assistant Professor (Hochschulassistent) at the University Göttingen where he received the Habilitation University Göttingen, venia legendi in 1988. From 1989 to 1997 he was Professor of Metalphysics (GKSS Research Centre, Geesthacht and Hamburg University of Technology) and from 1996 to 2009 he was director of the Institute for Materials Research, GKSS Research Centre, Geesthacht and since 2009 he is Professor of Applied Materials Physics and President of the University of Bayreuth

Prof. Rüdiger Bormann investigated 20 years ago the free energy of metallic glasses, metastable crystalline and amorphous alloys as well as the thermodynamics and kinetics of the amorphous phase formation by mechanical alloying. This was the basis for the investigation of Mg and Mg-Ni hydrides and the thermodynamics of nanoscale magnesim hydride. The discovery catalytic effect of metal oxides on the hydrogen sorption kinetics of magnesium was a great step forward in the development of hydrogen storage materials. Furthermore, very important was also the interpretation of the role of the grain boundaries for the diffusion of hydrogen in the passivating hydride phase formation. Recently the discovery of the so called reactive hydride composites by the combination of two hydrides has opened a new field of materials design for hydrogen storage. Therefore, we award Prof. Rüdiger Bormann with the Science of Hydrogen & Energy prize 2010.


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Prof. Dr. Ivor Rex Harris

Ivor Rex Harris was born August 31, 1939 in United Kingdom. In 1960 he rewceived his B.Sc. in Physical Metallurgy from the University of Birmingham), 1964 his Ph.D and became a ICI Research Fellow. From 1966 he was lecturer in the Department of Physical Metallurgy and1988he became a full Professor of Materials Science. From 1989 to 2002 he was Head of School, Metallurgy and Materials and from 2004 to 2005 acting director of the Institute for Energy Research and Policy. Since 2008 he is Honorary Professor of Materials Science of the School of Metallurgy and Materials at the University of Birmingham.

For around 40 years, Rex Harris was leader of the Applied Alloy Chemistry Group (AACG) in Metallurgy and Materials. During this time he maintained a long-standing research interest in the fields of rare earth alloys, permanent magnets and hydrogen purification and storage materials. He developed a close synergy between these fields with the development and application of the Hydrogen Decrepitation (HD) process to the manufacture of NdFeB magnets. The HD process resulted in up to a 25% saving in production cost and is now used world-wide in the fabrication of NdFeB sintered magnets. These materials are playing a vital role in the production of energy efficient electric drives, actuators and generators. The latest development within the group is the use of the HD process in the recycling of 2/17 and NdFeB magnets. His research also made a very significant contribution to the development and understanding of the Hydrogenation, Disproportionation, Desorption and Recombination (HDDR) process which enabled coercive powder and hence bonded magnets to be formed from bulk NdFeB alloys. He has published over 500 scientific papers and edited and co-edited a number of books. During these years he has successfully supervised around 120 postgraduate students, many of whom are still working in applied materials science and occupy senior positions in industry, government and academia throughout the world. Since stepping down as group leader and head of school he has focused his activities on the application of NdFeB magnets and hydrogen storage materials to practical demonstrators such as the Ross Barlow hybrid canal boat. This zero- carbon emission craft is serving to highlight the huge potential of magnets and hydrogen in the drive towards a sustainable transport system and he has given a large number of public lectures on this subject with the aim of raising public awareness of the dual threats of climate change and resource depletion. He continues to be very active in this campaign which he considers to be of paramount importance. Therefore, we award Prof. Rex Harris with the Science of Hydrogen & Energy prize 2010.


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Prof. Dr. Reiner Kirchheim

Reiner Kirchheim was born May 24, 1943 in Halle/Saale, Germany. He studied Physics at the University of Stuttgart from 1966-1971 and received the diploma for the work “Electrochemical studies of oxygen solid solutions in high melting metals” at the Max-Planck-Institut für Metallforschung/University of Stuttgart. He received his Ph.D. for the thesis entitled “Thermo- and electrotransport of oxygen and nitrogen in Va metals“ from the University of Stuttgart, Max-Planck-Institut für Metallforschung in 1973. In 1988 he received the Habilitation “Measurements and modelling of hydrogen solubility and diffusivity in disordered metal lattices“ from the University of Stuttgart, Faculty of Chemistry Metallurgy. Since 1993 he is Full Professor (Gustav Tamman Chair) University of Göttingen Göttingen Germany and Director Georg-August-Universitaet Goettingen, Institut für Materialphysik Göttingen Germany.

Prof. Reiner Kirchheim has investigated 30 years ago oxygen in metals, especially diffusion, thermotransport and thermopower of oxygen in transition metals and alloys. In 1980 he started to study diffusion of hydrogen in dillute alloys of copper and niobium in palladium. He developed an electrochemical method for the measurement of the hydrogen diffusion in palladium and palladium alloys and performed fundamental studies on the diffusion mechanism of interstitial species. The interaction of hydrogen with dislocations in palladion and the interpretation with a model based on the Fermi-Dirac distribution are of great importance for the understanding of the interstitial site occupation of hydrogen inalloys and amorphous metals. For the enormous contributions on the hydrogen dynamics and thermodynamics in metals as well as the hydrogen interaction with dislocations, grain bounderies and interfaces we award Prof. Reiner Kirchheim with the Science of Hydrogen & Energy prize 2010.


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PARTICIPANTS


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Akiba Etsuo, Prof. Dr. AIST ETRI Tsukuba Central 5, 1-1-1, Higashi JP-305-8565 Tsukuba

email: [email protected] Tel: +81-298-61-4541 Fax: +81-298-61-4541

Balog Sandor, Dr. ETH Zürich & Paul Scherrer Institut Laboratory for Neutron Scattering Villigen PSI CH-CH-5232 Villigen

email: [email protected] Tel: (41) 56 310 5586 Fax: : (41) 56 310 2939

Banach Ewa, Ms. Shell Global Solutions Innovation & Research Grasweg 31 NL-1031 HW Amsterdam

email: [email protected]

Beckmann-Kluge Martin, Mr. BAM Federal Institute for Materials Research and Testing Chemische Sicherheitstechnik Unter den Eichen 87 DE-12205 Berlin


Bellosta von Colbe Jose, Dr. GKSS REsearch Centre Geesthacht GmbH Instute of Materials Research Max Planck St. DE-21502 Geesthacht


Berke Heinz, Prof. Dr. University of Zurich Institute of Inorganic Chemistry Winterthurerstrasse 190 CH-8057 Zurich

email: [email protected] Tel: 0041635 4681 Fax: 00416356803

Bielmann Michael, Dr. EMPA Hydrogen and Energy Überlandstrasse 129 CH-8600 Dübendorf

email: [email protected] Tel: (+41) (44) 823 4342 Fax: (+41) (44) 823 4022

Boesenberg Ulrike, Dr. GKSS Research Centre Geesthacht Institute for Materials Research Max-Planck-Str. 1 DE-21502 Geesthacht

email: [email protected] Tel: 0049 4152 87 2565 Fax: 0049 4152 87 2625

Borgschulte Andreas, Dr. Empa Mobility, Environment, and Energy Ueberlandstrasse 129 CH-8600 Dübendorf


Bormann Rüdiger, Prof. Dr. University Bayreuth Universitätsstrasse 30 DE-95440 Bayreuth

email: [email protected] Tel: +491716150053

Boulouchos Konstantinos, Prof. Dr.

ETH Zürich Institute of Energy Technology Sonneggstrasse 3 CH-8092 Zürich


Buchter Florian, Dr. ABB Schweiz AG, Corporate Research Segelhofstrasse 1 CH-5405 Baden 5 Dättwil


Cakir Deniz, Dr. University of Twente Faculty of Science-Computational Materials Science HOGEKAMP 10162 NL-7500 AE Enschede

email: [email protected] Tel: +31 53 489 3155 Fax: +31-53-4892910


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Capurso Giovanni, Dr. University of Padova Mechanical Engineering - Materials Section Via Marzolo, 9 I-35131 Padova (Italy)

Email: [email protected]

Centi Gabriele, Prof Univ. Messina Dept Ind Chem and Eng Materials Salita Sperone 31 IT-98166 Messina

email: [email protected] Tel: +390906765609 Fax: +39090391518

Cho Young Whan, Dr. KIST Advanced Functional Materials Research CentrePO Box 131, Cheongryang KR-130-650 Seoul


Chung Moon-Sun, Dr. Korea Institute of Energy Research Hydrogen Energy R&D Centre 71-2 Jang-dong, Yuseong-gu KR-305-343 Daejoen


Churchard Andrew, Mr. ICM, University of Warsaw Chemistry Zwirki i Wigury 93 PL-02-089 Warsaw


Corno Marta, Dr. Università degli Studi di Torino Dipartimento di Chimica I.F.M via P. Giuria, 7 IT-10125 Torino

email: [email protected] Tel: 00390116704597

Dam Bernard, Prof. Dr. Delft University of Technology Applied Science Julianalaan 139 NL-2628 BL Delft


Domènech-Ferrer Roger, Mr. IFW 21 Helmholtzstraße DE-D-01069 dresden


Dornheim Martin, Dr. GKSS Research Centre Geesthacht Nanotechnology Max-Planck-Straße 1 DE-21502 Geesthacht


Er Süleyman, Dr. University of Twente Hogekamp Building. Room: 10164 NL-7500AE Enschede

email: [email protected] Tel: (+31)(53) 489 3167 Fax: (+31)(53) 489 2910

Fichtner Maximilian, Dr. KIT INT P.O. Box 3640 DE-76021 Karlsruhe

email: [email protected] Tel: +49 7247 825340

Filippi Matteo, Dr. Vrije University Physics and Astronomy De Boelelaan NL-1081 HV Amsterdam

email: [email protected] Tel: +31 20 598 7912 Fax: +31 20 598 7991

Friedrichs Oliver, Dr. Empa Hydrogen & Energy Ueberlandstrasse 129 CH-8600 Duebendorf



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Garroni Sebastiano, Mr. Universitat Autonoma de Barcelona Physics Department Edifici Cc(C3/210) ES-088193 Bellaterra


Gianola Corinne, Ms. Empa Hydrogen & Energy Überlandstrasse 129 CH-8600 Dübendorf

email: [email protected] Tel: +41448234692 Fax: +41448234022

Gil Bardají Elisa, Dr. Karlsruhe Institute of Technology Institut of Nanotechnology Hermann-von-Helmholtz Platz 1 DE-D-76344 Eggenstein-Leopoldshafen

email: [email protected] Tel: ++49 (0)7247 82 8909 Fax: ++49 (0)7247 82 6368

Gorbar Michal, Mr. Empa Hydrogen & Energy, Abt. 138 Überlandstrasse 129 CH-CH-8600 Dübendorf


Gregory Duncan, Prof. Dr. University of Glasgow Chemistry University Avenue GB-G12 8QQ Glasgow

email: [email protected] Tel: 00441413306438 Fax: 00441413304888

Gremaud Robin, Dr. Empa Hydrogen & Energy Überlandstrasse 129 CH-8600 Dübendorf


Gutfleisch Oliver, Dr. IFW Dresden IMW Helmholtzstr. 20 DE-01069 Dresden


Haggi Ahmed Abdirizak, Ms. Educational Institue BiaoChimic Wayaki way KE-00100-7556 Nairobi


Han Sang-Sup, Dr. Korea Institute of Energy Research Greenhouse Gas Research Centre 102 Gajeong-ro, Yuseong-gu KR-305-343 Daejon Metropolitan City


Harris Rex, Prof. Dr. Metallurgy and Materials The University of Birmingham Edgbaston Birmingham B15 2TT UK-

email: [email protected] Tel: (+44) (0) 121 414 5165 Fax: (+44) (0) 121 414 5247

Holtappels Kai, Dr. BAM Federal Institute for Materials Research and Testing Chemical Safety Engineering Unter den Eichen 87 DE-12205 Berlin


Hu Jianjiang, Dr. Karlsruhe Institute of Technology (KIT) Institute for Nanotechnology Hermann-von-Helmholtz Platz 1 DE-76344 Eggenstein-Leopoldshafen

email: [email protected] Tel: 0049 7247 828915 Fax: 0049 7247 82 6368

Jhi Seung-Hoon, Prof. Dr. Pohang University of Science and Technology Physics Hyojadong San 31 KR-790-784 Pohang



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Kato Shunsuke, Mr. Empa Dept. Environment, Energy and Mobility Überlandstrasse 129 CH-8600 Dübendorf

email: [email protected] Tel: +41 (44) 823 4327 Fax: +41 (44) 823 4022

Kiichi Kojima, Mr. Toyota motor Co, Fuel Cell System Engineering Div Toyotacho1-1 JP-471-0826 Toyota

email: [email protected] Tel: 81+565-72-9200 Fax: 81+565-23-0355

Kim Jaheon, Prof. Dr. Soongsil University Chemistry 511 Sangod-Dong Dongjak-Gu KR-156-743 Seoul


Kim Ji Woo, Mr. Seoul National University Materials Science and Engineering Gwanak KR-151-742 Seoul


Kirchheim Reiner, Prof. Dr. Friedrich-Hund-Platz 1 DE-D-37077 Goettingen


Kozlov Alexey, Dr. Institute of Coal and Coal Chemistry SB RAS Sovetskiy Avenue, 18 RU-650099 Kemerovo


Langhammer Christoph, Dr. Chalmers University of Technology Applied Physics Fysikgränd 3 SE-41296 Göteborg


Laurenczy Gabor, Dr. EPFL ISIC LCOM BCH CH-1015 Lausanne


Lee Nam-Hee, Dr. Sejong University Faculty of Nanotechnology and Advanced Materials 98Gunja-dong, Gwangjin-gu KR-143-747 Seoul


Lindemann Inge, Ms. IFW Helmholtzstraße 20 DE-D-01171 Dresden

email: [email protected] Tel: +49 (0)351-4659-669

Martelli Pascal, Mr. EMPA Hydrogen & Energy Ueberlandstrasse 129 CH-8600 Duebendorf


Matsuo Motoaki, Dr. Tohoku University Institute for Materials Research Katahira 2-1-1, Aobaku JP-980-8577 Sendai


Mauron Philippe, Dr. EMPA Hydrogen & Energy Ueberlandstrasse 129 CH-8600 Dübendorf



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Milanese Chiara, Dr. University of Pavia Department of Physical Chemistry Viale Taramelli, 16 IT-27100 Pavia

email: [email protected] Tel: +39-0382-987670 Fax: +39-0382-987670

Miwa Kazutoshi, Dr. Toyota Central R&D Labs., Inc. Computational Physics Lab. Nagakute JP-480-1192 Aichi


Muller Jiri, Dr. Institute for Energy Technology - IFE Box 40 NO-NO-2027 Kjeller

email: [email protected] Tel: 0047 63 80 61 85

Orimo Shin-ichi, Prof. Dr. Tohoku University Institute for Materials Research Katahira 2-1-1, Aobaku JP-980-8577 Sendai


Park Noejung, Prof. Dr. Dankook University Applied Physics 126, Jukjeon-dong, Suji-gu KR-448-701 Yongin-city


Pendolino Flavio, Mr. EMPA Hydrogen & Energy Uberlanstrasse 129 CH-8600 Dubendorf


Pistidda Claudio, Mr. GKSS Max-Planck-Straße 1 DE-21502 Geesthacht


Ramirez-Cuesta Anibal Dr. STFC ISIS GB-OX11 0QX Chilton

email: [email protected] Tel.: (044) 7787105335

Remhof Arndt, Dr. Empa Hydrogen & Energy Ueberlandstrasse 129 CH-8600 Duebendorf


Rongeat Carine, Ms. IFW Dresden Institute for Metallic Materials Helmholtzstrasse 20 DE-01069 Dresden

email: [email protected] Tel: +49 (0)351-4659-669

Ronnebro Ewa, Dr. Pacific Northwest National Laboratory 509 Battelle Boulevard US-99354 Richland

email: [email protected] Tel: Fax:

Schaer Roland, Mr. Hilti AG Advanced mechatronics Technisches Zentrum FL-9494 Schaan

email: [email protected] Tel: 00423 234 2321

Schiavo Benedetto, Mr. Università degli Studi di Palermo Department of Physics and related Technologies Viale delle Scienze, bdg n.18 IT-90100 Palermo



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Shim Jae-Hyeok, Dr. Korea Institute of Science and Technology Advanced Functional Materials Research Center39-1 Hawolgok-dong, Seongbuk-gu KR-136-791 Seoul


Stojadinovic Jelena , Dr. Empa Duebendorf Hydrogen and Energy Ueberlandstrasse 129 CH-8600 Duebendorf


Stowe Ashley, Dr. B&W Y-12 national Security Complex Technology Development 301 Bear Creek Road MS8097 US-37831 Oak Ridge


Suh Jin-Yoo, Dr. Korea Institute of Science and Technology Materials Science and Technology Research Division 39-1 Hawolgok-dong, Seongbuk-gu KR-136-791 Seoul

email: [email protected] Fax: +82-2-958-5379

Taube Klaus, Dr. GKSS-Forschungszentrum Geesthacht GmbH Nanotechnology Max-Planck-Strasse 1 DE-D-21502 Geesthacht

email: [email protected] Tel: +49 4152 872541 Fax: +49 4152 872625

Utz Inga, Ms DLR (German Aerospace Center) Institute of Technical Thermodynamics Pfaffenwaldring 38-40 DE-70569 Stuttgart

email: [email protected] Tel: 0049 (0)711 6862 492

Vogt Ulrich, Dr. EMPA Senior Scientist Ueberlandstr. 129 CH-8600 Duebendorf


Walton Allan, Dr. University of Birmingham Metallurgy and Materials Pritchats Road GB-B152TT Birmingham

email: [email protected] Tel: 44 121 414 3960

Wiedenmann Daniel, Mr. Empa Abt. 138 Überlandstrasse 129 ch-8600 Dübendorf


Zakaznova-Herzog Valentina, Dr.

Empa Duebendorf Hydrogen & Energy Ueberlandstrasse 129 CH-8600 Duebendorf


Züttel Andreas, Prof. Dr. EMPA Materials Science & Technology Energy, Environment and Mobility Sec. Hydrogen & Energy Überlandstrasse 129 CH-8600 Dübendorf



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Information


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Map from Zürich (upper left corner) to Wildhaus (lower right corner)

Map of the region Wildhaus


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Map of Wildhaus

EMERGENCY TELEPHONE NUMBERS POLICE 117 FIRE FIGHTERS 118 AMBULANCE 144 RESCUE HELICOPTER 1414 Corinne Gianola 076 398 9985 Andreas Züttel 079 215 4601 Hotel Hirschen Wildhaus, Reception 071 998 5454


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Wildhaus Region


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TIMETABLE


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NOTES


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Documents

Hydrogen & Energy Symposium Wildhaus, Switzerland 2010 th ... · Modelling, Fuel Cells, Metal Hydride Batteries, Functional Materials ... Here the electrochemical conversion on the