Regulated Cu x -Ga0.9-In0.1 Oxides Based on Cu Active Site for High-Efficiency Electrocatalytic CO2 Reduction to CO

Abstract Due to its unique electronic structure and suitable active sites, Cu is a promising catalyst for CO2 reduction. In this study, a series of Cux-Ga0.9-In0.1 oxides was synthesized via co-precipitation by varying Cu2+ concentration. X-ray diffraction and X-ray photoelectron spectroscopy reveal that Cu exists as CuO, Ga forms Ga2O3 due to its strong oxophilicity, and a small amount of In is uniformly dispersed as In2O3 within the CuO lattice, forming a composite catalyst. Combined density functional theory calculations and X-ray absorption fine structure spectroscopic analyses indicate Cu as the primary active site. The introduction of Ga and In enhances electron transfer with Cu, strengthening intermediate adsorption and accelerating product conversion, thereby improving catalytic performance for the CO2 reduction reaction. When the molar ratio of divalent to trivalent ions n(M2+):n(M3+) is 5:1, the catalyst achieves a total current density of 28.4 mA·cm–2, a CO Faradaic efficiency of 98.54%, and good stability.