Electrochemical reduction of CO₂ to ethane through stabilization of an ethoxy intermediate

Abstract

Electrochemical conversion of CO2 to ethane is seldom observed because of the generally higher selectivity towards methane, ethylene, and ethanol. Consequently, little experimental evidence for its reaction mechanism exists and thus remains largely unknown. Here, by combining electrochemistry with in-situ X-ray absorption fine structure and in-situ Raman techniques, we study iodide-derived copper (ID-Cu) and oxide-derived copper (OD-Cu) systems to obtain a deeper understanding of the CO2 to ethane mechanism. With trace iodine species on the surface and positively charged Cu species, production of ethane is significantly more favored on ID-Cu compared to OD-Cu, with higher selectivity and faster kinetics. For the first time, it is experimentally found that the formation of ethane follows the same pathway to ethylene and ethanol, and better stabilization of the late stage ethoxy intermediate can steer the reaction to ethane over ethanol.