Optimizing C─C Coupling on Cu⁰/Cu⁺/Ga Interfaces by Enhancing Active Hydrogen Absorption for Excellent CO₂-to-C₂₊ Electrosynthesis

The electrocatalytic reduction of CO₂ (CO₂RR) to high-value chemicals and fuels offers a promising route for a clean carbon cycle. However, it often suffers from low catalytic activity and poor selectivity. Heterostructure construction has been shown to be an effective strategy for producing multi-carbon products, but the synergistic mechanisms between multiple active sites resulting from the reconstruction process remain unclear. In this study, a Ga₂O₃/CuO heterostructure is established via a simple sol–gel method to produce C₂₊ products. Experimental results demonstrate that Ga₂O₃ stabilizes Cu⁺ to form Cu⁰/Cu⁺/Ga active centers and enhances water-splitting ability during the reaction. The improved hydrogen absorption on the Ga site shifts the C─C coupling reaction pathway from ^*OCCO to the asymmetric ^*OCCHO coupling path with a lower energy barrier. As a result, the catalysts exhibit superior CO₂RR performance, achieving a 70.1% C₂₊ Faradaic efficiency at −1.2 V_RHE in a flow cell, with ethylene Faradaic efficiency reaching 58.3% and remaining stable for 10 h.