Asymmetric Cu Sites for Enhanced CO2 Electroreduction to C2+ Products

Cu-based electrocatalysts can have excellent activity for the generation of C2+ products from a CO2 reduc-tion reaction (CO2RR). Cu delta+ species is crucial in tun-ing the performance of the catalysts. Herein, we discovered that Si-doped Cu catalysts had excellent performance for electrochemical CO2 to C2+ pro-ducts. A high Faradaic efficiency (FE) of 84.7% was achieved with a current density of 289 mA cm-2 in the flow-cell system. In situ experimental results showed that the significant reconstruction occurred during the electrolysis, resulting in the formation of the asymmetric Cu sites (Cu degrees-Cu+). The ratio of Cu degrees and Cu+ could be tuned by changing Si content. Con-trolled experiments and theoretical calculations demonstrated that the asymmetric Cu sites caused by the appropriate Si doping promoted CO2 activation and strengthened the adsorption of *CO intermediate. This was beneficial to the subsequent *CO-*CO dimerization step, and thus, accounted for enhancement of C2+ selectivity.