Enhanced electroreduction of CO2 to ethanol via enriched intermediates at high CO2 pressures

Electrochemical conversion of CO2 into liquid fuels such as ethanol, powered by renewable electricity, is an efficient strategy for CO2 utilization to produce high value-added products. In this work, we discovered that the primary C2+ product could be switched from gaseous ethylene to liquid ethanol by directly increasing the CO2 pressure when Cu2O@Cu with a hollow sphere morphology was adopted as the catalyst. The faradaic efficiency (FE) of ethanol reached as high as 36.6% at a low overpotential of -1.0 V vs. Ag/AgCl (-0.48 V vs. RHE) at 100 bar, which was 4.6 times higher than that of 1 bar. Moreover, faster kinetics and lower overpotential for ethanol formation were obtained at high CO2 pressures. In situ Raman spectroscopy studies at different pressures in combination with density functional theory calculations demonstrated that the *CO surface coverage was increased significantly at increased CO2 pressure, which is responsible for facilitating ethanol formation during the electrochemical CO2RR. This study provides a novel and promising strategy for the selective production of ethanol on Cu-based catalysts by facilely adjusting the CO2 pressure.