Engineering COBridge Adsorption in Cu2O-TiO2 Heterojunction Catalyst for Selective Electrochemical CO2 Reduction to Ethanol

Selective electroreduction of carbon dioxide (CO2) into multicarbon products using copper-based catalysts, primarily governed by CO adsorption configurations such as atop-adsorbed *CO (COatop) and bridge-adsorbed *CO (CObridge), is a promising strategy for converting greenhouse gases into valuable chemicals and fuels. However, the production of ethanol (C2H5OH), a crucial chemical feedstock, is significantly limited by weak CObridge adsorption on copper-based catalysts. Herein, a Cu2O-TiO2 heterostructure catalyst was designed to adjust the CO adsorption configurations for promoting the selectivity of ethanol. At an applied potential of −0.7 V vs RHE, Cu2O-TiO2 demonstrated a 5.1-fold increase in the Faradaic efficiency (FE) for C2H5OH (27.13%) compared to that of Cu2O (5.2%). Experimental and theoretical calculation results verified the strong electronic interactions between Cu2O and TiO2 in Cu2O-TiO2, resulting in an increase in the valence state of Ti and consequently enhancing the oxophilicity of TiO2. Moreover, carbon monoxide temperature-programmed desorption (CO-TPD) results, in situ Raman spectra, and DFT calculations revealed a more robust CObridge adsorption on the Cu2O-TiO2 surface than on Cu2O due to the improved oxophilicity of TiO2, which is responding for the better ethanol selectivity of the electrocatalytic CO2 reduction reaction (CO2RR). This work offers original insights into the design of electrocatalysts for the selective production of ethanol from the CO2RR by engineering CO adsorption configurations.