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  • 1. 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
  • 2. Presentation Outline Introduction Idea behind the work Development of Protocol Validation Results References
  • 3. Electrochemical Reduction of Carbon Dioxide Breaches 400 ppm on May 9th, 2013 Ref U.S. EIA, monthly energy review, Table 1.3, March 2012 Dec. 10-12, 2013 ICAER – 2013 3
  • 4. Possible options for the mitigation of excess CO2 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. Dec. 10-12, 2013 ICAER – 2013 4
  • 5. 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
  • 6. Why Electrochemical reduction of Carbon Dioxide ?  Reactions can be carried out at ambient temperature and pressure conditions  Co-reactant is Water  Need of electrical energy can be fulfilled using renewable energy resources (Source: Olah et al., JOC Perspective, 74 (2), 2009) Dec. 10-12, 2013 ICAER – 2013 6
  • 7. Electrochemical Reduction of Carbon Dioxide (ERC) Anode Cathode Anode Reaction: 2H2O 4H+ + 2e- + O2 Cathode Reactions: CO2 + 2H+ + 2eHCOOH CO2 + 2H+ + 2eCO + H2O CO2 + 6H+ + 6eCH3OH + H2O CO2 + 8H+ + 8eCH4 + 2H2O Dec. 10-12, 2013 ICAER – 2013 Eo = - 1.23 V vs. SHE Eo = - 0.225 V vs. SHE Eo = - 0.103 V vs. SHE Eo = + 0.031 V vs. SHE Eo = + 0.169 V vs. SHE 7
  • 8. Challenges to overcome 1 2 Activate this thermodynamically stable molecule The actual electrolysis potential for CO2 reduction is much more negative than the eq. potential 3 4 Product separation and analysis 5 Dec. 10-12, 2013 Simultaneous production of Hydrogen Difficult to achieve the selectivity of products ICAER – 2013 8
  • 9. Use of ELECTROCATALYSTS How to screen an electrocatalyst from the group of many ? Dec. 10-12, 2013 ICAER – 2013 9
  • 10. Conventional Approach : Cyclic Voltammetry (CV) Ex. Cu, Sn, CuO etc. N2 Atmosphere: Aqueous KHCO3 solution, bubbled with N2 - pH 8.5 CO2 Atmosphere: Aqueous KHCO3 solution, saturated with CO2 - pH 7.5 Dec. 10-12, 2013 Ex. Mo2C etc. Anomaly : Ag, Ni, Co3O4 etc. ICAER – 2013 10
  • 11. Development of Protocol Dec. 10-12, 2013 ICAER – 2013 11
  • 12. 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 Electrocatalyst may not be active for ERC (particularly in aqueous medium) NO YES Current increased in presence of catalyst Electrocatalyst may be active for ERC INFERENCE Increased current may be due to increased H+ reduction / CO2 reduction or both Test the electrocatalyst activity towards H+ reduction 2nd Test: In KOH aqueous solution (pH 7.5) Get LSV in presence and absence of catalyst H+ NO Electrocatalyst is not active for reduction INFERENCE Electrocatalyst may be active only towards ERC Current increased in presence of catalyst YES Electrocatalyst is also active for H+ reduction INFERENCE Electrocatalytic activity has to be checked esp. for CO2 reduction in absence of H+ ion 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 Electrocatalyst is inactive for CO2 reduction NO Current increased in presence of catalyst YES Electrocatalyst may work for ERC INFERENCE Full Cell reaction can be attempted
  • 13. Electrocatalysts Selection Cu Commercially Purchased Dec. 10-12, 2013 CuO Synthesized through Aqueous Precipitation method Co3O4 Synthesized through Polymer Combustion Route ICAER – 2013 ZnO Synthesized through Aqueous Precipitation method Mo2C Commercially Purchased 13
  • 14. Characterization of the Electrocatalysts - XRD ZnO CuO Mo2C Dec. 10-12, 2013 ICAER – 2013 Co3O4 14
  • 15. Characterization of the Electrocatalysts - FESEM CuO Mo2C Dec. 10-12, 2013 ZnO Co3O4 ICAER – 2013 15
  • 16. Characterization of the Electrocatalysts – EDX & FTIR CuO Co3O4 Dec. 10-12, 2013 ICAER – 2013 ZnO Co3O4 16
  • 17. Characterization of the Electrocatalysts – BET surface area  9.9 m2/g  ZnO 15.9 m2/g  Mo2C 5.8 m2/g  Dec. 10-12, 2013 CuO Co3O4 9.2 m2/g ICAER – 2013 17
  • 18. ‘Cyclic Voltammetry’ tests using selected electrocatalysts Cu Mo2C ZnO CuO Dec. 10-12, 2013 Co3O4 ICAER – 2013 18
  • 19. ‘Protocol Results’ using selected electrocatalysts Protocol Results 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) 1st Test: CO2 sat. Aq. KHCO3 solution 2nd Test: KOH solution 3rd Test: CO2 bubbled DMF ( j denotes the current density) Dec. 10-12, 2013 ICAER – 2013 19
  • 20. Comparison of the results of Proposed Protocol with CV test Activity of Electrocatalysts Electrocatalysts CV Cu √ √ CuO √ √ ZnO ~ √ Mo2C X X Co3O4 Dec. 10-12, 2013 Proposed Protocol X √ ICAER – 2013 20
  • 21. Full Cell Reaction using electrocatalysts CO2 saturated aq. KHCO3 Water inlet Gas chromatography (GC) Cathode Anode High performance liquid chromatography (HPLC) Cathode outlet O2, H2O outlet Electrocatalysts Electrolyte Product Yield (%) CuO Nafion Methanol 8.7 % ZnO Nafion Methanol 5.4% Co3O4 Nafion Formaldehyde 1.78% Dec. 10-12, 2013 ICAER – 2013 21
  • 22. Summary Objective 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 Dec. 10-12, 2013 Protocol Development A new protocol has been developed for the quick screening of electrocatalysts. Validation Results Various electrocatalysts were selected to validate the protocol. The protocol was found valid for all the electrocatalysts tested. Electrocatalysts were characterized physicochemically. ICAER – 2013 22
  • 23. 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
  • 24. Thank You!!

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