Identification of CO2 as a Reactive Reagent for C–C Bond Formation via Copper-Catalyzed Electrochemical Reduction

The electrochemical reduction of CO2 (CO2ER) holds great promise as a method to achieve carbon neutrality and revolutionize the utilization of fossil fuels. Advanced catalysts used in CO2ER have demonstrated the ability to generate valuable multi-carbon products through the formation of carbon–carbon (C–C) bonds. Previous research has predominantly focused on C–C formation by dimerizing *CO or coupling *CO with other *C1 intermediates. However, the potential coupling of CO2 with *C1 intermediates has not been explored experimentally or theoretically despite CO2 being the exclusive reactant in CO2ER and having a high concentration. This study employed DFT calculations and a constant electrode potential model to investigate the possibility of CO2 + *C1 couplings on Cu(100) surfaces. Surprisingly, the results indicate that CO2 can serve as a favorable reagent for C–C bond formation, surpassing the reactivity of *CO under alkaline conditions. The enhanced reactivity of CO2 compared to that of *CO was elucidated based on a barrier decomposition analysis. Experimental validation was conducted to confirm these theoretical results.