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

Selective electroreduction of carbon dioxide (CO 2 ) into multicarbon products using copper-based catalysts, primarily governed by CO adsorption configurations such as atop-adsorbed *CO (CO atop ) and bridge-adsorbed *CO (CO bridge ), is a promising strategy for converting greenhouse gases into valuable chemicals and fuels. However, the production of ethanol (C 2 H 5 OH), a crucial chemical feedstock, is significantly limited by weak CO bridge adsorption on copper-based catalysts. Herein, a Cu 2 O-TiO 2 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, Cu 2 O-TiO 2 demonstrated a 5.1-fold increase in the Faradaic efficiency (FE) for C 2 H 5 OH (27.13%) compared to that of Cu 2 O (5.2%). Experimental and theoretical calculation results verified the strong electronic interactions between Cu 2 O and TiO 2 in Cu 2 O-TiO 2, resulting in an increase in the valence state of Ti and consequently enhancing the oxophilicity of TiO 2 . Moreover, carbon monoxide temperature-programmed desorption (CO-TPD) results, in situ Raman spectra, and DFT calculations revealed a more robust CO bridge adsorption on the Cu 2 O-TiO 2 surface than on Cu 2 O due to the improved oxophilicity of TiO 2, which is responding for the better ethanol selectivity of the electrocatalytic CO 2 reduction reaction (CO 2 RR). This work offers original insights into the design of electrocatalysts for the selective production of ethanol from the CO 2 RR by engineering CO adsorption configurations.