Rare-Earth Y-O Skeleton-Mediated Stabilization of Cu²⁺ for Efficient CO₂ Electroreduction to CH₄

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.