Surface Hydroxyl-Mediated Stabilization of Cu + Species in Ga-Doped Cu 2 O Catalysts for Sustained CO 2 Electroreduction to Ethylene

The presence of surface hydroxyl (*OH) species plays a critical role in modulating the selectivity and stability of Cu 2 O catalysts during CO 2 electroreduction to ethylene and ethanol. However, the underlying mechanism by which *OH adsorption contributes to Cu 2 O stability remains poorly understood. In this study, we report the development of a Ga-doped Cu 2 O (Ga–Cu 2 O) catalyst, where Ga promotes the adsorption of *OH species on the catalyst surface. This enhanced *OH adsorption strengthens Cu–O interactions and improves the stability of Cu + species. In situ Raman spectroscopy and theoretical calculations reveal that Ga incorporation facilitates *OH formation, which in turn increases orbital overlap between Cu 3d and O 2p orbitals. This interaction suppresses lattice oxygen leaching and contributes to the stabilization of Cu + . As a result, Ga–Cu 2 O exhibits a stable ethylene production rate sustained for over 50 h, achieving a Faradaic efficiency (FE) for C 2 H 4 of 26.4%, which is 1.4 times higher than that of pure Cu 2 O. These findings offer mechanistic insights into the role of the catalyst microenvironment in Cu + stabilization during CO 2 RR and provide valuable guidance for the rational design of more efficient and durable CO 2 reduction catalysts.