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

Abstract

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.