Enhancing CO2 Electroreduction Performance through Si-Doped CuO: Stabilization of Cu+/Cu0 Sites and Improved C2 Product Selectivity

Cu-based catalysts leveraging Cu+/Cu0 active sites have emerged as pivotal for synthesizing essential hydrocarbons and alcohols in electrochemical CO2 reduction, such as ethylene and ethanol (C2 products). However, the dynamic reduction of Cu+ to Cu0 during electroreduction leads to site instability, resulting in diminished efficiency for CO2 conversion to C2 products. Herein, we introduced Si into CuO by the selective dissolution method, engendering Cu–O–Si units to stabilize the Cu+/Cu0 sites. The catalyst manifested good activity in CO2 electroreduction with an elevated Faradaic efficiency for C2 products reaching 81.9% at −100 mA/cm2. After ten cycles of electrochemical testing, the Cu+/Cu0 sites and performance exhibited no signs of degradation. The Si incorporation significantly improved the hybridization of O 2p and Cu 3d orbitals, thereby reinforcing the Cu–O bonds and stabilizing the Cu+/Cu0 sites, which was critical in promoting C–C coupling via decreasing the energy barriers for *OCCO formation and enhancing C2 product selection. The active Cu+ cations with unsaturated coordination contributed to the reaction stabilization, thereby improving the preservation of Cu2O metastable state.