(191d) Enhancing the Selectivity for Electrocatalytic CO2 Reduction By Oscillating Applied Potential

The aqueous electrochemical CO₂ reduction reaction (CO2RR) is of crucial environmental, societal, and industrial importance. One of the major caveats of aqueous CO2RR is the presence of a dominant hydrogen evolution reaction (HER) which severely impacts the efficiency of CO2RR. Various combinations of the electrocatalysts, electrolytes, and electrochemical cells have been explored to increase the suppression of HER and thereby increasing the overall efficiency of CO2RR but most of the work shows a trade-off between high-flux and high-selectivity of CO2RR for a specific product over HER. Moreover, almost all the existing literature shows CO2RR at a constant static applied potential under which the near-surface concentration of CO₂ undergoes rapid depletion and eventually leads to HER becoming the dominant reaction. To enhance the selectivity toward CO2RR, here we explore the implementation of the catalytic resonance by oscillating the turnover frequency of the CO2RR intermediates at the catalyst surface. This oscillation is achieved by perturbing the catalyst surface with varying frequencies and amplitudes of the applied potential to determine the catalytic resonance of the kinetics of CO2RR over HER. The faradaic efficiency (FE) of ethylene and consequently, the selectivity of CO2RR over a Cu-mesh catalyst in aqueous electrolytes in a packed bed electrochemical cell over a range of static applied potentials and oscillating applied potentials at different frequencies and amplitudes will be discussed as a part of this work.