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.