Regulated Reconstruction of the Cu ⁺ /Cu ²⁺ Heterointerface by Cerium MOFs for the Efficient CO ₂ Electroreduction to C ₂ Products

Copper-based heterointerfaces are recognized as efficient active sites for electrochemical CO2 reduction reactions (CO2RR) to C2 products but suffer from instability due to the surface reconstruction under operational potentials. Herein, we report a strategy combining the Cu+/Cu2+ heterointerface and hydrophobic microenvironment via the in situ reconstruction of a cerium metal–organic framework (Ce-BDC) modified Cu foil. Through tuning the drop-casting volume, we can regulate the Cu surface evolution to achieve the optimal Cu+/Cu2+ ratio. Moreover, the remaining hydrophobic microenvironment synergistically facilitates CO2 adsorption and inhibits the hydrogen evolution reaction (HER). As a result, the optimized 1.0-Ce-BDC/Cu-R catalyst achieves a remarkable C2 Faradic efficiency of 66.0% at −1.2 V vs RHE and maintains excellent stability over 13 h of continuous operation. Density functional theory (DFT) calculations further elucidate the critical role of the stabilized Cu+/Cu2+ heterointerface: strengthened *CO adsorption and reduced C–C coupling energy barrier (0.39 eV vs 6.57 eV on Cu+ sites). This study provides a route to design efficient heterointerfaces for CO2 reduction to C2 products.