Revisiting the electrochemical reduction of CO2 on Au25(SR)18− nanocluster

Abstract

Experiments show that Au25(SR)18− is a potential electrocatalyst for the electrochemical reduction of CO2, but elucidation of the reaction mechanisms remain challenging experimentally. We evaluate key steps in the active site formation, CO2 reduction, and H2 evolution on the nanocluster employing density functional theory coupled with an explicit solvent model of the electrochemical interface to calculate activation barriers. The predicted preferred pathway for activating the nanocluster involves dethiolation, resulting in an exposed Au site that is both active and selective for CO2 reduction. The alternative S site is found to be kinetically prohibitive and does not facilitate CO2 reduction.