Ag as an Electron Mediator in Porous Cu2O Nanostructures for Photocatalytic CO2 Reduction to CO

Cuprous oxide (Cu2O) has attracted tremendous attention in the field of photocatalytic CO2 conversion due to excellent optical character and carrier separation efficiency. However, photocatalytic CO2 conversion is a multiple proton-coupled electron transfer process that usually produces various products, and it is still a major challenge for improving the yield and selectivity of CO2 to a single product. Herein, a low-temperature deposition method combined with the dynamic hydrogen bubble template method was used to synthesize a Ag/Cu2O photocatalyst to tackle this problem. The Ag/Cu2O photocatalyst has porous nanostructures and exhibits excellent performance in photocatalytic CO2 reduction. The CO yield of Ag/Cu2O-0.04 is 22.52 nmol cm–2 h–1 (43.04 μmol g–1 h–1), which is about 1.5 times that of the original sample. For the selectivity of CO, Ag/Cu2O was increased by 22% compared with Cu2O, reaching 82.9%. Combined with density functional theory and Fourier transform infrared spectroscopy, it is found that Ag loading changes the adsorption configuration of CO2 on the catalyst from bidentate carbonate to monodentate carbonate, improving the selectivity of CO. In addition, the Ag/Cu2O Schottky junction accelerates the surface reaction kinetics due to acceleration of the separation and transportation of photogenerated carriers. Therefore, this work provides an idea to develop a high-efficient photocatalyst for photocatalytic CO2 reduction.