Enhancing CO<sub>2</sub> Electroreduction Performance through Si-Doped CuO: Stabilization of Cu<sup>+</sup>/Cu<sup>0</sup> Sites and Improved C<sub>2</sub> Product Selectivity
Long Cheng, Rong Wang, Wenzhe Si, Yanxi Deng, Junhua Li, Yue Peng
Abstract
Cu-based catalysts leveraging Cu + /Cu 0 active sites have emerged as pivotal for synthesizing essential hydrocarbons and alcohols in electrochemical CO 2 reduction, such as ethylene and ethanol (C 2 products). However, the dynamic reduction of Cu + to Cu 0 during electroreduction leads to site instability, resulting in diminished efficiency for CO 2 conversion to C 2 products. Herein, we introduced Si into CuO by the selective dissolution method, engendering Cu–O–Si units to stabilize the Cu + /Cu 0 sites. The catalyst manifested good activity in CO 2 electroreduction with an elevated Faradaic efficiency for C 2 products reaching 81.9% at −100 mA/cm 2 . After ten cycles of electrochemical testing, the Cu + /Cu 0 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 + /Cu 0 sites, which was critical in promoting C–C coupling via decreasing the energy barriers for *OCCO formation and enhancing C 2 product selection. The active Cu + cations with unsaturated coordination contributed to the reaction stabilization, thereby improving the preservation of Cu 2 O metastable state.