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

Cuprous oxide (Cu 2 O) has attracted tremendous attention in the field of photocatalytic CO 2 conversion due to excellent optical character and carrier separation efficiency. However, photocatalytic CO 2 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 CO 2 to a single product. Herein, a low-temperature deposition method combined with the dynamic hydrogen bubble template method was used to synthesize a Ag/Cu 2 O photocatalyst to tackle this problem. The Ag/Cu 2 O photocatalyst has porous nanostructures and exhibits excellent performance in photocatalytic CO 2 reduction. The CO yield of Ag/Cu 2 O-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/Cu 2 O was increased by 22% compared with Cu 2 O, reaching 82.9%. Combined with density functional theory and Fourier transform infrared spectroscopy, it is found that Ag loading changes the adsorption configuration of CO 2 on the catalyst from bidentate carbonate to monodentate carbonate, improving the selectivity of CO. In addition, the Ag/Cu 2 O 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 CO 2 reduction.