Synergistic modulation of valence state and oxygen vacancy induced by surface reconstruction of the CeO2/CuO catalyst toward enhanced electrochemical CO2 reduction

Electrochemical CO₂ reduction reaction (CO₂RR) offers a promising strategy for CO₂ conversion into value-added C₂₊ products and facilitates the storage of renewable resources under comparatively mild conditions, but still remains a challenge. Herein, we propose the strategy of surface reconstruction and interface integration engineering to construct tuneable Cu⁰–Cu⁺–Cu²⁺ sites and oxygen vacancy oxide derived from CeO₂/CuO nanosheets (OD-CeO₂/CuO NSs) heterojunction catalysts and promote the activity and selectivity of CO₂RR. The optimized OD-CeO₂/CuO electrocatalyst shows the maximum Faradic efficiencies for C₂₊ products in the H-type cell, which reaches 69.8% at −1.25 V versus a reversible hydrogen electrode (RHE). Advanced characterization analysis and density functional theory (DFT) calculations further confirm the fact that the existence of oxygen vacancies and Cu⁰–Cu⁺–Cu²⁺ sites modified with CeO₂ is conducive to CO₂ adsorption and activation, enhances the hydrogenation of *CO to *CHO, and further promotes the dimerization of *CHO, thus promoting the selectivity of C₂₊ generation. This facile interface integration and surface reconstruction strategy provides an ideal strategy to guide the design of CO₂RR electrocatalysts.