Reconstructed rich oxygen defects and Ag⁰ on Pr₆O₁₁ surface through interface-defect engineering for enhanced electrochemical carbon dioxide reduction

The design of catalysts for electrochemical CO₂ reduction (ECR) is a key challenge for achieving efficient conversion of CO₂ into fuels. By concentrating on the active sites of the surface, the strategy of interface and defect engineering has proven effective in enhancing reactivity. Herein, we developed a new Ag/Pr₆O₁₁ nanocomposite catalyst with rich interfaces and oxygen defect structures, which induced the in-situ formation of more oxygen vacancies and Ag⁰ on Pr₆O₁₁ during the initial period of ECR. The catalyst exhibits a Faradaic efficiency of 98% for the conversion of CO₂ to CO and a mass activity of 48.4 A g⁻¹ at the overpotential of −1.09 V. The metal-support interface active sites and oxygen vacancy defects at the Ag/Pr₆O₁₁ interface enhance interfacial catalytic activity and promote CO₂ adsorption and activation. Additionally, in-situ infrared and Raman spectroscopy confirmed that the presence of oxygen vacancies and the interface-modified Ag/Pr₆O₁₁ enhanced the local microenvironment on the catalyst surface. This improvement accelerated the adsorption and conversion of the key intermediate *COOH, thereby increasing the intrinsic activity of the ECR process and contributing to the inhibitory effect on the hydrogen evolution reaction (HER). This straight forward strategy of interface integration and surface reconstruction offers a potentially versatile approach for guiding the design of ECR electrocatalysts.