Copper-based catalysts show considerable promise in the electrochemical CO2 reduction reaction (CO2RR) for the production of hydrocarbons and oxygenates, particularly methane (CH4), which is a highly reduced product. The high-valent state of copper (Cu) exerts a positive influence on the formation pathway of CH4, but the reduction potential will lead to a decrease in the valence state during CO2RR. In this study, a highly crystalline and structurally well-defined Y2Cu2O5 catalyst is constructed to stabilize Cu2+ with the orderly alternating Y─O skeleton layer, owing to the strong bonding interaction. The Y2Cu2O5 exhibits a remarkable enhancement in CH4 selectivity compared to CuO (up to 9.59-folds), achieving a selectivity of 61.3% at 300 mA cm-2 and 58.4% at 400 mA cm-2, together with good stability. In situ attenuated total reflectance Fourier transform infrared spectra (ATR-FTIR) and density functional theory (DFT) calculations reveal that the presence of the Y─O skeleton layer in Y2Cu2O5 significantly enhances the adsorption of *CO intermediate, and accelerates its hydrogenation process, facilitating the conversion of CO2 to CH4. This work highlights Y─O skeleton-mediated stabilization of Cu2+ for efficient electroreduction of CO2 to CH4, providing valuable insights into the design of efficient electrocatalysts for CO2 conversion.
Keywords: CH4 selectivity; CO2 electroreduction; Cu2+ site; Y─O skeleton layer; inhibit reconstruction.
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