S.J. Percival, D. Richards, C. Leverant,S. Rempe, J. Venegas, E.D. Spoerke
Sandia National Laboratories,
United States
Keywords: Carbon dioxide, Electrocatalysis, CO2 Reduction, Capture and Conversion, Reactive Capture, Ionic Liquids
Summary:
The electrochemical CO2 reduction reaction (CO2RR) is emerging as a promising method to produce carbon neutral chemical feedstocks. Additives or co-catalysts in the electrolyte can lower the activation barrier for CO2RR, yielding faster conversion rates at lower voltages. Recently, electrocatalytic CO2 reduction mediated by ionic liquids (IL) has been reported but with conflicting accounts to whether the ILs benefit CO2RR or the competing hydrogen evolution reaction (HER). We report the effect of added IL EMIM-Cl, specifically EMIM+, in aqueous solutions on the electrochemical CO2RR and competing HER on gold. We show the CO2 reduction current increases with the added EMIM+ relative to the pure electrolyte. Differential pulse voltammetry reveals an additional large change in the reduction current that only appears with both CO2 and EMIM+ present. Lastly, we use advanced electrochemical analysis methods to determine the reaction kinetics and preliminary evidence shows that the standard heterogeneous rate constant increases for the reaction at large overpotentials while the HER is suppressed at low overpotentials with EMIM+ present. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525. SAND2023-11159A