Influence of Copper Surfaces on CO2 vs. CO C‐C Coupling Efficiency

Abstract

CO2 electrochemical reduction (CO2ER) powered by renewable electricity is critical for transitioning to a carbon‐neutral society by transforming CO2 into essential commodities and fuels. The formation of multi‐carbon compounds through C‐C coupling reactions is crucial due to their high energy density and broad industrial uses. Traditionally, C‐C coupling was believed to occur through the reaction of *CO (surface‐bound CO) with *C1 intermediates (surface‐bound hydrocarbons with one carbon atom produced during CO2ER). In this study, we used DFT calculations combined with a constant electrode potential model to discover a preference for CO2 + *C1 over conventional *CO + *C1 coupling on three commonly observed copper surfaces including Cu(111), Cu(110), and Cu(100). This result demonstrates that CO2 is a more efficient carbon source than *CO for coupling with *C1. Among the nine *C1 species investigated, *CHO, *CHOH, *C, *CH, and *CH2 show greater reactivity towards CO2 + *C1 couplings on all the surfaces. Thus, enhancing CO2ER efficiency necessitates increasing the surface concentrations of these five *C1 intermediates, and several strategies have been proposed to accomplish this goal.