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 neutralityand revolutionize the utilization of fossil fuels. Advanced catalystsused in CO2ER have demonstrated the ability to generatevaluable multi-carbon products through the formation of carbon-carbon(C-C) bonds. Previous research has predominantly focused onC-C formation by dimerizing *CO or coupling *CO with other*C-1 intermediates. However, the potential coupling of CO2 with *C-1 intermediates has not been explored experimentallyor theoretically despite CO2 being the exclusive reactantin CO2ER and having a high concentration. This study employedDFT calculations and a constant electrode potential model to investigatethe possibility of CO2 + *C-1 couplings on Cu(100)surfaces. Surprisingly, the results indicate that CO2 canserve as a favorable reagent for C-C bond formation, surpassingthe reactivity of *CO under alkaline conditions. The enhanced reactivityof CO2 compared to that of *CO was elucidated based ona barrier decomposition analysis. Experimental validation was conductedto confirm these theoretical results.