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

Abstract CO 2 electrochemical reduction (CO 2 ER) powered by renewable electricity is critical for transitioning to a carbon‐neutral society by transforming CO 2 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 *C 1 intermediates (surface‐bound hydrocarbons with one carbon atom produced during CO 2 ER). In this study, we used DFT calculations combined with a constant electrode potential model to discover a preference for CO 2 +*C 1 over conventional *CO+*C 1 coupling on three commonly observed copper surfaces including Cu(111), Cu(110), and Cu(100). This result demonstrates that CO 2 is a more efficient carbon source than *CO for coupling with *C 1 . Among the nine *C 1 species investigated, *CHO, *CHOH, *C, *CH, and *CH 2 show greater reactivity towards CO 2 +*C 1 couplings on all the surfaces. Thus, enhancing CO 2 ER efficiency necessitates increasing the surface concentrations of these five *C 1 intermediates, and several strategies have been proposed to accomplish this goal.