GLOBAL CLIMATE AND ENERGY PROJECT | STANFORD UNIVERSITY Insights into the electrochemical reduction of CO 2 on metal surfaces Kendra Kuhl Etosha R. Cave, David N. Abram, Toru Hatsukade Prof. Thomas F. Jaramillo Chemical Engineering Stanford University GLOBAL CHALLENGES – GLOBAL SOLUTIONS – GLOBAL OPPORTUNITIES GCEP RESEARCH SYMPOSIUM 2012 | STANFORD, CA
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GLOBAL CLIMATE AND ENERGY PROJECT | STANFORD UNIVERSITY
Insights into the electrochemical reduction of CO2 on metal surfaces
Kendra Kuhl Etosha R. Cave, David N. Abram, Toru Hatsukade
Prof. Thomas F. Jaramillo
Chemical Engineering
Stanford University
GLOBAL CHALLENGES – GLOBAL SOLUTIONS – GLOBAL OPPORTUNITIES
GCEP RESEARCH SYMPOSIUM 2012 | STANFORD, CA
Chemicals
Reduction
Goals
CxHyOz + O2 CO2 + H2O + Energy
CO2 + H2O + Energy CxHyOz + O2
2
CxHyOz + O2 CO2 + H2O + Energy
Electrochemistry
3
Water Oxidation (Anode) CO2 Reduction (Cathode)
Eο 1.23 V ~0 V
Overall Reaction:
O OHC Energy OH CO 2zyx22
)e 4(H O O2H -
22
OnH OHC )e m(H CO 2zyx
-
2
Need a Catalyst: Efficient + Selective
Fuels + Chemicals Overpotential:
-1 V
H )e 2(H 2
- 0 V Hydrogen Evolution:
CO2 Electroreduction Literature
4
Products determined by CO binding energy
X
Metals that bind CO strongly: Pt, Ni, Fe
Hydrocarbons, Alcohols
Metals that bind CO weakly: Au, Ag, Zn Intermediate CO binding: Cu
Andrew A. Peterson , Frank Abild-Pedersen , Felix Studt , Jan Rossmeisl and Jens K. Nørskov Energy Environ. Sci., 2010,3, 1311-1315
2e-, 2H+ Reduction
ne-, nH+ Reduction
Goal: better understanding of mechanism
CO2 Metal Surface
CO
H2
Electrolysis
5
Anode H2O O2 + 4(H+ + e-)
Cathode CO2 + m(H+ + e-) CxHyOz + H2O
4.5 cm2
electrode area 8 mL electrolyte volume
0.1 M KHCO3 electrolyte pH 6.8
Gas chromatograph for gas phase products
NMR for liquid phase products
Anode H2O O2 + 4(H+ + e-)
Cathode CO2 + m(H+ + e-) CxHyOz + H2O
0.1 M KHCO3 electrolyte pH 6.8
Gas chromatograph for gas phase products
NMR for liquid phase products
Transition Metals
• Cu, Ag, Au, Zn show good current efficiency for CO2 reduction
6 Increasing Overpotential
Weak CO binding
Strong CO binding
Intermediate CO binding
Metal H2 CO CH4 CH3OH C2’s HCOO-
Au
Ag
Zn
Cu
Pt
Ni
Fe
Products
• Major products match literature reports
• Hydrocarbon and/or alcohol production detected on all metals due to increased sensitivity of experimental setup
7
+
Major Products
Minor Products
Novel Products
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Products on Cu
Reported Few Reports Novel
8
e-’s C1 C2 C3
Useful products!
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18
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Products on Cu
Reported Few Reports Novel
9
e-’s C1 C2 C3
Methane: main component of natural gas Ethylene: used to produce plastics