Insight into CO Activation over Cu(100) under Electrochemical Conditions

Abstract The reduction of CO 2 on copper electrodes has attracted great attentions in the last decades, since it provides a sustainable approach for energy restore. During the CO 2 reduction process, the electron transfer to CO ads is experimentally suggested to be the crucial step. In this work, we examine two possible pathways in CO activation, i.e. to generate COH ads and CHO ads , respectively, by performing the state-of-the-art constrained ab initio molecular dynamics simulations on the charged Cu(100) electrode under aqueous conditions, which is close to the realistic electrochemical condition. The free energy profile in the formation of COH ads via the coupled proton and electron transfer is plotted. Furthermore, by Bader charge analyses, a linear relationship between C-O bond distance and the negative charge in CO fragment is unveiled. The formation of CHO ads is identified to be a surface catalytic reaction, which requires the adsorption of H atom on the surface first. By comparing these two pathways, we demonstrate that kinetically the formation of COH ads is more favored than that of CHO ads , while CHO ads is thermodynamically more stable. This work reveals that CO activation via COH ads intermediate is an important pathway in electrocatalysis, which could provide some insights into CO 2 electroreduction over Cu electrodes.