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Development of Catalytic Activity Protocol for Electrochemical Reduction of Carbon Dioxide
Surya Singh
Centre for the Environment
Indian Institute of Technology Guwahati
Guwahati, Assam – 781 039
Presentation Outline
Introduction
References
Results
Validation
Development of Protocol
Idea behind the work
Electrochemical Reduction of Carbon Dioxide
Dec. 10-12, 2013 ICAER – 2013 3
Breaches 400
ppm on May 9th,
2013
Ref U.S. EIA, monthly energy review, Table 1.3, March 2012
Decrease in fossil fuel consumption and other activities which result in CO2 emission
Effective use of technologies to reduce CO2 emission to the atmosphere
Capture CO2 and dump it in geologic or oceanic reservoirs
Utilize CO2 by converting it to either fuels or some other value added products, resulting in two fold advantages:
a. Reduction in CO2 level b. Reducing the dependency over conventional non-renewable fossil fuels, thus enhancing
energy security.
Possible options for the mitigation of excess CO2
Dec. 10-12, 2013 ICAER – 2013 4
Utilization of CO2 for the production of value added products
(Ref. Viswanathan B., Proc. Ind. Acad. Sci., 70 A (3), 2004)
Dec. 10-12, 2013 ICAER – 2013 5
Dec. 10-12, 2013 ICAER – 2013 6
Why Electrochemical reduction of Carbon Dioxide ?
Reactions can be carried out at ambient temperature and pressure conditions
(Source: Olah et al., JOC Perspective, 74 (2), 2009)
Co-reactant is Water Need of electrical energy can be fulfilled using renewable energy resources
Electrochemical Reduction of Carbon Dioxide (ERC)
Anode Reaction: 2H2O 4H+ + 2e- + O2
Eo = - 1.23 V vs. SHE
Cathode Reactions: CO2 + 2H+ + 2e- HCOOH Eo = - 0.225 V vs. SHE
CO2 + 2H+ + 2e- CO + H2O Eo = - 0.103 V vs. SHE
CO2 + 6H+ + 6e- CH3OH + H2O Eo = + 0.031 V vs. SHE
CO2 + 8H+ + 8e- CH4 + 2H2O Eo = + 0.169 V vs. SHE
Dec. 10-12, 2013 ICAER – 2013 7
Anode Cathode
Dec. 10-12, 2013 ICAER – 2013 8
11 Activate this thermodynamically stable moleculeActivate this thermodynamically stable molecule
44 Product separation and analysisProduct separation and analysis
55 Difficult to achieve the selectivity of productsDifficult to achieve the selectivity of products
Challenges to overcome
33 Simultaneous production of Hydrogen
22 The actual electrolysis potential for CO2 reduction is
much more negative than the eq. potential
How to screen an electrocatalyst from the group
of many ?
Dec. 10-12, 2013 ICAER – 2013 9
Use of ELECTROCATALYSTS
Conventional Approach : Cyclic Voltammetry (CV)
Ex. Cu, Sn, CuO etc.
Dec. 10-12, 2013 ICAER – 2013 10
Anomaly : Ag, Ni, Co3O4 etc.
Ex. Mo2C etc.
N2 Atmosphere: Aqueous KHCO3 solution, bubbled with N2 - pH 8.5
CO2 Atmosphere: Aqueous KHCO3 solution, saturated with CO2 - pH 7.5
Development of Protocol
Dec. 10-12, 2013 ICAER – 2013 11
Select a probable electrocatalyst for ERC based upon literature and experience
Test its activity towards ERC (aqueous medium)
1st Test: In 0.5 M aqueous KHCO3, saturated with CO2 (pH 7.5)
Get LSV in presence and absence of catalyst
Current increased in presence of catalyst Electrocatalyst may be active for ERCINFERENCE
Increased current may be due to increased H+ reduction / CO2 reduction or both
Electrocatalyst may not be active for ERC (particularly in aqueous medium)
YESNO
Electrocatalyst is also active for H+ reductionElectrocatalyst is not active for H+
reductionElectrocatalyst may be active only
towards ERCElectrocatalytic activity has to be checked esp. for CO2 reduction in absence of H+ ion
YES
Test the electrocatalyst activity towards H+ reduction
2nd Test: In KOH aqueous solution (pH 7.5)
Get LSV in presence and absence of catalyst
Current increased in presence of catalystNO
INFERENCE INFERENCE
Test the electrocatalyst activity towards ERC (non aqueous medium)
3rd Test: In DMF, bubbled with CO2 (pH 7.5)
Get LSV in presence and absence of catalyst
Current increased in presence of catalyst Electrocatalyst may work for ERC
Full Cell reaction can be attempted
Electrocatalyst is inactive for CO2 reduction
YESINFERENCE
NO
Synthesized through Aqueous
Precipitation method
Synthesized through Polymer
Combustion Route
Commercially Purchased
Synthesized through Aqueous
Precipitation method
Commercially Purchased
Cu CuO Co3O4 ZnO Mo2C
Electrocatalysts Selection
Dec. 10-12, 2013 ICAER – 2013 13
Characterization of the Electrocatalysts - XRD
CuO ZnO
Co3O4Mo2C
Dec. 10-12, 2013 ICAER – 2013 14
Dec. 10-12, 2013 ICAER – 2013 15
Characterization of the Electrocatalysts - FESEM
CuO ZnO
Co3O4Mo2C
Characterization of the Electrocatalysts – EDX & FTIR
CuO ZnO
Co3O4
Dec. 10-12, 2013 ICAER – 2013 16
Co3O4
Characterization of the Electrocatalysts – BET surface area
Dec. 10-12, 2013 ICAER – 2013 17
CuO
ZnO
Mo2C
Co3O4
9.9 m2/g
15.9 m2/g
5.8 m2/g
9.2 m2/g
Dec. 10-12, 2013 ICAER – 2013 18
CuO
ZnO
Mo2CCu
Co3O4
‘Cyclic Voltammetry’ tests using selected electrocatalysts
Electrocatalysts 1st Test (% j) 2nd Test (% j) 3rd Test (% j)
Cu Yes (146) Yes (38) Yes (52)
CuO Yes (21) Yes (13) Yes (32)
ZnO Yes (19) Yes (18) Yes (20)
Mo2C No (~ 0) Not Applicable No (~ 0)
Co3O4 Yes (28) Yes (21) Yes (45)
Protocol Results
Dec. 10-12, 2013 ICAER – 2013 19
‘Protocol Results’ using selected electrocatalysts
( j denotes the current density)
1st Test: CO2 sat. Aq. KHCO3 solution2nd Test: KOH solution3rd Test: CO2 bubbled DMF
Electrocatalysts
Cu
CuO
ZnO
Mo2C
Activity of Electrocatalysts
CV Proposed Protocol
Co3O4
X X
X
√
√√
√
~
√
√
Comparison of the results of Proposed Protocol with CV test
Dec. 10-12, 2013 ICAER – 2013 20
CO2 saturated aq. KHCO3
Water inlet
O2, H2O outlet
Cathode outlet
AnodeCathode
Full Cell Reaction using electrocatalysts
Dec. 10-12, 2013 ICAER – 2013 21
Electrocatalyst
s
Electrolyte Product Yield (%)
CuO Nafion Methanol 8.7 %
ZnO Nafion Methanol 5.4%
Co3O4Nafion Formaldehyde 1.78%
Gas chromatography (GC)
High performance liquid chromatography (HPLC)
A new protocol has been developed for the quick screening of electrocatalysts.
Various electrocatalysts were selected to validate the protocol.
Electrocatalysts were characterized physico-chemically.
The protocol was found valid for all the electrocatalysts tested.
The problem in quick selection of an electrocatalyst from a group of many, was identified as a major issue in the field of electrochemical reduction of carbon dioxide
Objective Protocol Development
Validation Results
Summary
Dec. 10-12, 2013 ICAER – 2013 22
Acknowledgements First and Foremost thanks to my supervisors Dr. Anil Verma & Dr. Chandan Mukherjee for their sagacious guidance, suggestions and sustained encouragement. Thanks to the National Program on Carbon Sequestration Research, DST, New Delhi for the financial support vide project grant number DST/IS-STAC/CO2-SR-139/12(G).
Heartful gratitude to my research group members: • Ms. Lepakshi Barbora• Mr. Avijit Ghosh• Mr. Leela M. Aeshala• Mr. V. Shyam K. Yadav• Mr. Ehtesham Hussain• Mr. Rajamahendra Rapally
Thank You!!