Carbon Recycling Technology Based on … Speech_III_190910.pdfClean Coal Day in 2019 10 th September 2019 1 Photocatalysis International Research Center (PIRC) Tokyo University of

Clean Coal Day in 201910th September 2019

1Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)

Carbon Recycling Technology

Based on Photocatalysis

Akira FujishimaDistinguished Professor of Tokyo University of Science

Director, Photocatalysis International Research Center, TUS

How great the solar energy is!

2

Hydrogen → Helium0.6 billion tons/sec

1/2.2 billionth of output reaches to the Earth

Energy problem is solved only by 1 hour within 1 year!

Make Solar on the Earth!Research on nuclear fusion

Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)


4

Z-scheme and Calvin cycle in photosynthesis

Water Splitting (O2) CO2 Reduction


5

Success of water photolysis by TiO2 photocatalysis


6

Cross-sectional image of TiO2 electrode

From Dr. thesis“Photoelectrode Reaction ofSemiconductors”


Cu lead

Epoxy resin

TiO2 (001) single crystal

7

Production of Oxygen


Discovery of water photolysisA. Fujishima, K. Honda Nature (1972)

Success in water photolysis by rutile TiO2 single crystalStill attracting great interests


Facile production of large-size TiO2

Develop large-size and high-efficient TiO2only burning Ti sheet by burner


Burning of Ti sheet

Burner Lead

Epoxy resin

Wiring a lead and sealing by epoxy resin

A. Fujishima, K. Kohayakawa, K. Honda, J. Electrochem. Soc. 1975, 122, 1487.

Only 6.6 L/day of H2 produced from TiO2 (per 1m2)

Attempt to produce H2 under solar lightH2 production experiment under solar light by filling TiO2 sheets


H2 production experiment under solar light

1. TiO2 electrode2. Pt electrode3. Salt bridge


12

More than 6×1023 photons are required toproduce H2 by decomposing 1 mol of water(18 g) on 1 cm2 of TiO2.

Actual solar light (and even fluorescent)contains much photons than E. Coli (106) on1 cm2 of TiO2.

Photon density of solar light: 1015 photons/cm2

n hν

Considering the energy efficiency, usage such as decomposition of bacteria is realistic than H2 production.

Change in thinking


13

Bactericidal effect

Evaluation for sterilization ability




Smoking room in Shinkansen N700 series: Deodorizer with photocatalyst

16

Discovery of super hydrophilicity

Wang, R.; Hashimoto, K.; Fujishima, A. Nature 1997, 388, 431

Hydrophobic TiO2

Hydrophilic TiO2J. Phys. Chem. B 2001, 105, 3023


17

Mirror with photocatalyst

Coating on side-view (wing) mirrors


18

Practical application as a self-cleaning material dramatically expands

Self-cleaning effect by photocatalystSelf-cleaning effect by decomposition of organics and super hydrophilicity


Weak oil stains are decomposedby strong oxidation power.

Strong oil stains are removed bywater using super hydrophilicity.



21

GRANROOF (Tokyo Station, Yaesu Exit)


22

AT&T Stadium (Cowboys Stadium)(Dallas, Texas)

Example in USA


23

Photocatalyst in various uses


24東京理科大学光触媒国際研究センター

Opened in 2013

Established by theInnovation CenterEstablishmentAssistance Programby the Ministry ofEconomy, Trade andIndustry (METI)

25

Introduction in World Economic Forum (Davos Forum)by Japanese Prime Minister Abe’s keynote lecture

There is artificial photosynthesis,

for which a key discovery, one

for photocatalysis, was made by

Akira Fujishima, a Japanese

Scientist.

YOMIURI ONLINE January 23, 2019 19:58


26

Overview of the proposal

Solar Energy CO2

H2, CO

Methanol

Useful Materials

Water

(by oil/coal usage)

Photocatalyst/electrode


Photocatalyst/electrode

R & D Trend of Artificial Photosynthesis in the World


Recording the efficiency of artificial photosynthesis


Water Splitting

Recording the efficiency of artificial photosynthesis


CO2 Reduction

R & D Trend of Artificial Photosynthesis in USA

In 2010, Joint Center for Artificial Photosynthesis (JCAP) was established by Department of Energy(DOE).

1st term（〜Sep. 2015）Focus on solar hydrogen

2nd term（Oct. 2015 〜 2020）Solar energy conversion CO2 into chemical fuel

Res. fund: ＄75 million for 5 years（¥ 8.36 billion）

California Institute of TechnologyLawrence Berkeley National LaboratoryUniversity of California, IrvineUniversity of California San DiegoStanford University SLAC National Accelerator Laboratory

They has aimed to promote the oxidation reaction of water and the reduction reaction of CO2 on the front and back sides using an integrated device.

Organization


Japan Technological Research Association of Artificial Photosynthetic Chemical Process (ARPChem) in METI

Project period: 2012 〜 2021 (10 years) Total: ¥ 1.5 billionThe future pioneering research project of METI and MEXT

Development a photocatalyst system with 10% solar-hydrogen conversion efficiency Aim to produce basic chemicals such as plastic raw materials from hydrogen and CO2

obtained by water splitting by photocatalyst using solar energy.

Expected system Research organization

5 companies, 1 group participate


Approach to artificial photosynthesis research by company

Company System Production E (%)*1 Year

NTT Photoelectrode H2 0.84 2017TOTOMitsubishi Chemical Photoelectrode H2 3.7 2018

Panasonic Photoelectrode HCOOHCH4

0.20.04

20122013

Toshiba Photoelectrode CO 1.5 2014Toyota Central R&D Labs Photoelectrode HCOOH 4.6 2014

Showa Shell Sekiyu Photoelectrode CH4C2H4

0.610.1 2016

Others Fujitsu: Development of electrode for photosynthesis (light reaction) (2016）

*1 Conversion efficiency from solar energy to products.

Water splitting

CO2reduction


Important points in material development

• Strong oxidative power by light irradiation (water also decomposes)However, TiO2 does not decompose.

• Absorbs ultraviolet light (transparent)• Sufficient resources• Safe (good to eat)

Characteristics of TiO2

Other Semiconductors• Absorbs visible light (colored)• Easily decomposed in water

(water and organic substances can not be decomposed)• Problem with resources• Toxicity


Clear problem

1. Solar energy conversion efficiency

2. Stability

3. Scale-up

4. Cost (inexpensive material)

5. Flexible reaction conditions

(Acid, alkali, sacrificial reagent free)


Concentrated multi-junction solar cell

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5

0.3 0.8 1.3 1.8 2.3 2.8 3.3 3.8

Phot

on fl

ux (m

-2eV

-1)

Photon Energy (eV)

16.912.126.7

Phot

on fl

ux (m

-2s-1

eV-1

)

Multi-junction cells

InGaP

GaAs

Ge

Fresnel lens

1MW CPV plant @Masen, MoroccoCurtesy of Sumitomo Electric

Cell efficiency: 42～46%Module efficiency: 30～33%

35Prof. Sugiyama (Tokyo Univ.)

Solar light → H2 Maximizing energy efficiency

Direct connection of high efficiency solar cells and electrolysis cells

Moduleunder

development CPV modules

Electrochemical Cells

Electrical connection

H106

H103CPV modules

E106(2 cells in a package)

CPV mono-modules

E103

H2collection

O2collection

VA

Clamp ammeter

STH efficiency: 24.4%(Demonstrated outdoors in Miyazaki)

36Prof. Sugiyama (Tokyo Univ.)

CO2 Reduction


Diamond Electrodes

●炭素(C)

●ホウ素(B)

Boron-doped Diamond (BDD)

ドープなし

Insulator

(cm-3)

p-Type Semiconductor

0 %[B] / [C]

[B]

Diamond Electrodes

Metal10-2Ωcm

Cutting tools

Active in several application

Power devices

~ 1018 1019 1020 1021 1022

0.01 % 0.1 % 1 %


Diamond Synthesis by Microwave Plasma CVD

Raman Spectrum

sp3Carbon 1333 cm-1

Plasma

Quartz plate

Substrate

Microwave

Vacuum pump

Carbon source

H 2

H2

+Polycrystalline Diamond

1000 1100 1200 1300 1400 1500 1600 1700Raman Shift (cm-1)

Inte

nsity

(a.u

.)

B(OCH3)3


Wide Potential Window of Diamond Electrodes

Direct CO2 Reductionwith selectivity

Ozone generation

Oxygen evolution

Hydrogen evolution

H2

H2

O2


(–2.1 V vs. Ag/AgCl)

CO2 Reduction by Diamond Electrodes●Switchable product selectivity

CO（Carbon monoxide） HCOOH（Formic acid）

CO2 + 2H+ + 2e- → CO + H2O

CO2• ‒

CO2• ‒

J. Am. Chem. Soc., 141, 7414 (2019).

41Prof. Einaga (Keio Univ.)

42

Rapid Synthesis of Diamond by In-liquid Plasma

Diamond Relat. Mater., 2016, 63, 12

Diamond Relat. Mater., 2019, 92, 41

Reactor

Growth rate c.a. 170μm/h(MPCVD method : 1~2 μm/h)

Prof. Terashima (Tokyo Univ. of Sci.)

Our Proposal for Carbon Recycling Technology


Solar energy(Electrical energy)

Electrochemical CO2 reductionat diamond electrode

Power generationIndustries Chemicals

Fuels

CO2

Vision of Future Society by Photocatalysis

Source: URL from Photocatalysis International Research Center at Tokyo University of Sciencehttps://www.rs.tus.ac.jp/pirc/


Thank you for your kind attention


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Carbon Recycling Technology Based on … Speech_III_190910.pdfClean Coal Day in 2019 10 th September 2019 1 Photocatalysis International Research Center (PIRC) Tokyo University of