Surface Engineering of Copper Catalyst through CO* Adsorbate

Abstract

The electrochemical reduction of CO2 with Cu-based catalysts depends intimately on the instantaneous local chemical environment of the catalyst–electrolyte interface. This microenvironment fluctuates according to the concentration of surface-adsorbed competing reaction intermediates and the applied electrode potential. In practice, disentangling these factors is exceedingly challenging, yet they critically determine the electrocatalyst efficiency and selectivity. Using grand canonical quantum-classical hybrid calculations, we quantify the complex interdependence between electrode potential, CO* coverage, and the interfacial field strength. We show that the often overlooked CO* coverage effect in fact strongly influences the field strength, with a magnitude change exceeding 1 V/Å at certain potentials; among other effects, this change should lower the CO* dimerization barrier that dictates selectivity toward multicarbon products. Beyond showcasing the importance of surface coverage for CO2 reduction, our results highlight the power of surface additives to modulate interfacial fields toward tailored electrochemical pathways.