מצגת של PowerPoint · מצגת של PowerPoint Author: Lior Elbaz Created Date: 5/9/2019 3:43:37 AM

IEA Topical Meeting, Berlin, Nov. 15th, 2017

Lior ElbazIsraeli Fuel Cells Consortium (Head)

Bar-Ilan University, Ramat-Gan, Israel [email protected]

mailto:[email protected]


Motivation

Accelerating the development of PGM-free electrocatalysts for next-generation fuel cells


PGM-free catalysts are a key research goal for moving towards DOE’s ultimate$30/kW target (D. Papageorgopoulos, Annual Merit Review and Peer Evaluation Meeting,

Washington, DC, June 5-9, 2017)

Motivation


US-DOE Technical Targets


Biology

Oxygen Reduction Reaction (ORR)

Fuel Cells

5


Unsolved Problems in Electrocatalysis of Oxygen Reduction

Low Turnover Frequencies

Thermodynamic Barrier (Pt)

H. Gastieger et al., Science, 2009, 324,48.

I. Stephens et al., Energy Environ. Sci., 2012, 5, 6744.

Stability

Elbaz et al., J. Power Sources, 2016

U.S. Geological Survey Fact Sheet 087-02 (2002)

Low abundance of precious metals

Turnover Frequencies

Thermodynamic Barrier (Pt)


I. Stephens et al., Energy Environ. Sci., 2012, 5, 6744.

Stability

Elbaz et al., J. Power Sources, 2016

Low abundance of precious metals

U.S. Geological Survey Fact Sheet 087-02 (2002)U.S. Geological Survey Fact Sheet 087-02 (2002)

6

IEA Topical Meeting, Berlin, Nov. 15th, 2017J.P. Collman et al., J. Am. Chem. Soc., 2002

Precious Group Metal-Free ORR Catalysts

J-P. Dodelet et al., Nature Comm., 2011P. Zelenay et al., Science, 2011

MolecularPyrolyzed

R. Jasinski, Nature, 1964, 201, 1212

Pyrolysis Sophisticated synthesis

Activity

StructureStability

Synthesis

Pros

Cons

Activity

Structure

Pros

Cons

Stability

Synthesis6


Sub groups of PGM-free ORR catalysts for PEMFCs

PGM-Free Pyrolyzed M-N-C

Metal-Organic Frame works

Macrocyclic compounds

Molecular

Enzymatic

Macrocyclic compounds

Bio-mimetic

Metal-free???


1964


2e- reduction to H2O2:

Co(III)P + e- Co(II)P

Co(II)P + O2 Co(III)P __ O2.-

Co(III)P __ O2.- + 2H+ Co(III)P + H2O2

Consecutive reduction of H2O2 to H2O:

Co(III)P + e- Co(II)P

Co(II)P + H2O2 Co(III)P __ H2O2.-

Co(III)P __ H2O2.- + 2H+ Co(III)P + 2H2O

Proposed ORR Mechanism – Electrochemical Chemical


1964 1969

Jahnke, H.; Schoenborn, M.; Presses Acad. Eur: 1969, p 60-65.

1) Improved Activity

2) Improved Stability

3) Unknown structure!

Heat Treated Phthalocynines


1964 1969 1964 - 1976

Jahnke, H.; Schonborn, M.; Zimmermann, G. (1976)

Organic dyestuffs as catalysts for fuel cells. Top Curr

Chem 61: 133-181.


b-Substituents

R2 =

Elec

tro

neg

ativ

ity

meso-Substituents

R1 =

Three Key Parameters

Metal Center


1964 1969 1964 - 1976 1976-1980


1964 1969 1964 - 1976 19801976-1980

Fukuzumi, S.; Okamoto, K.; Gros, C. P.;

Guilard, R. JACS 2004, 126, 10441.


1964 1969 1964 - 1976 1980 1980-2000 2000-Today


Biomimetic Electrocatalysis of Oxygen Reduction

Very active, very expensive and not so stable.

http://web.stanford.edu/group/collman/cco.htm


1964 1969 1964 - 1976 1980 1980-2000 2000-Today


Mn

Fe

Co

Ni

Cu

ORR Onset Potential (in acid) (V vs. RHE)

0.81

0.720.69

0.480.46

Electrocatalysis of ORR with Molecular Catalysts


1964 1969 1964 - 1976 1980 1980-2000 2000-Today

van Veen, J. A. R.; van Baar, J. F.; Kroese, K. J. (1981) J Chem

Soc, Faraday Trans 1: Phys Chem in Condensed Phases 77

(11): 2827-2843.

Schulenburg, H.; Stankov, S.; Schünemann, V.; Radnik, J.;

Dorbandt, I.; Fiechter, S.; Bogdanoff, P.; Tributsch, H. (2003) J

Phys Chem B 107 (34): 9034-9041.

MN4/C Catalysts


1964 1969 1964 - 1976 1980 1980-2000 2000-Today

Wu, G.; Chung, H. T.; Nelson, M.; Artyushkova, K.; More, K. L.;

Johnston, C. M.; Zelenay, P. (2011) ECS Trans 41 (1): 1709-

1717.

Li, X.; Popov, B. N.; Kawahara, T.; Yanagi, H. (2011) J Power

Sources 196 (4): 1717-1722.


1964 1969 1964 - 1976 1980 1980-2000 2000-Today

J.Y. Cheon et al., Nature 2013 (3) 2715


State-of-the-Art - Pyrolyzed

MOFs M-N-Cs

P. Zelenay, annual merit review presentation 2016 D.J. Liu et al., ChemElectroChem, 2016, 3, 1541



Catalytic Site Density, is this the Answer?


Durabilty


Co(III)P + e- Co(II)PCo(II)P + O2 Co(II)-O2

Co(II)-O2 + 3e- + 4H+ Co(III) +H2O

Stable

Not Stable

Catalyst Degradation Mechanism


Solution: Molecular Catalysts as Model Structures

Characterization

SynthesisModelling

Design


Future Work

Catalyst Activity:

• Increase site density• Tune porosity to enhance mass transfer• Understand structure-activity relationship

Durability:

• Use durable non-carbon supports• Minimize and eliminate spectator species in Fe-based

catalysts• Improve durability by advance cathode design


Commercialization: Pajarito Powder

Advisory Board

Prof. Piotr Zelenay

Prof. Plamen Atanssov

Prof. Sanjeev Mukerjee

Prof. Hubert Gasteiger

Prof. Scott Calabrese-Barton

Prof. J-P Dodelet


Commercialization: Ballard-Nisshinbo

“platinum, which goes for some 4,000 yen ($36.35) per gram. Replacing it with a catalyst using Nisshinbo's carbon alloy, which costs less than 1 yen per gram”

Ballard has successfully incorporated the Non Precious Metal Catalyst into a high performing catalyst layer under a Technology Solutions program and plans to launch a new 30-watt FCgen®-1040 fuel cell stack product incorporating NPMC for commercial use in late-2017.


Products: GenCell


Conclusions

• PGM-free are needed in order to further reduce fuel cells price

• PGM-free catalysts can be divided into two major groups: Pyrolyzed and Molecular

• Pyrolyzed catalysts are considered to be the most active

• Durability and Site density are still big challenges

• Further development of 3D networks is showing great promise

• Industry has began adopting PGM-free catalysts and use them in commercial fuel cells


Thank you!

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מצגת של PowerPoint · מצגת של PowerPoint Author: Lior Elbaz Created Date: 5/9/2019 3:43:37 AM