–CH3 Mediated Pathway for the Electroreduction of CO2 to Ethane and Ethanol on Thick Oxide-Derived Copper Catalysts at Low Overpotentials

Abstract

Oxide-derived copper is known for its unique ability to catalyze the selective electroreduction of CO2 to C2 and higher carbon compounds at low overpotentials. To understand this phenomenon, mechanistic studies typically chose ethylene (C2H4) as the model compound. The pathways to form other C2 compounds such as ethane (C2H6) and ethanol are then generally considered to be similar to that of C2H4. However, regular detection of C2H6 or ethanol on thick oxide-derived Cu at low overpotentials, often with selectivities exceeding that of C2H4, raises an important question: does the formation of these two C2 molecules really share a common route with C2H4? In this work, through an investigation of CO2 electroreduction on oxide-derived Cu of different thicknesses and oxidation states, we show that the formation of C2H6 and ethanol on thick oxide-derived Cu films could proceed through routes distinct from that of C2H4 at low overpotentials. Investigations using select molecular precursors such as diacetyl [(CH3CO...