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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)
3Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
4
Z-scheme and Calvin cycle in photosynthesis
Water Splitting (O2) CO2 Reduction
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
5
Success of water photolysis by TiO2 photocatalysis
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
6
Cross-sectional image of TiO2 electrode
From Dr. thesis“Photoelectrode Reaction ofSemiconductors”
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
Cu lead
Epoxy resin
TiO2 (001) single crystal
7
Production of Oxygen
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
Discovery of water photolysisA. Fujishima, K. Honda Nature (1972)
Success in water photolysis by rutile TiO2 single crystalStill attracting great interests
8Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
Facile production of large-size TiO2
Develop large-size and high-efficient TiO2only burning Ti sheet by burner
9Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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
10Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
H2 production experiment under solar light
1. TiO2 electrode2. Pt electrode3. Salt bridge
11Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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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
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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Bactericidal effect
Evaluation for sterilization ability
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
14Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
15Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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Mirror with photocatalyst
Coating on side-view (wing) mirrors
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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Practical application as a self-cleaning material dramatically expands
Self-cleaning effect by photocatalystSelf-cleaning effect by decomposition of organics and super hydrophilicity
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
Weak oil stains are decomposedby strong oxidation power.
Strong oil stains are removed bywater using super hydrophilicity.
19Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
20Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
21
GRANROOF (Tokyo Station, Yaesu Exit)
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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AT&T Stadium (Cowboys Stadium)(Dallas, Texas)
Example in USA
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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Photocatalyst in various uses
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
26
Overview of the proposal
Solar Energy CO2
H2, CO
Methanol
Useful Materials
Water
(by oil/coal usage)
Photocatalyst/electrode
Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
Photocatalyst/electrode
R & D Trend of Artificial Photosynthesis in the World
27Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
Recording the efficiency of artificial photosynthesis
28Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
Water Splitting
Recording the efficiency of artificial photosynthesis
29Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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
30Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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
31Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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
32Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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
33Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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)
34Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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
37Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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 %
38Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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
39Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
Wide Potential Window of Diamond Electrodes
Direct CO2 Reductionwith selectivity
Ozone generation
Oxygen evolution
Hydrogen evolution
H2
H2
O2
40Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
(–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
43Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
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/
44Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)
Thank you for your kind attention
45Photocatalysis International Research Center (PIRC) Tokyo University of Science (TUS)