Space-Confined Growth of Cs2CuBr4 Perovskite Nanodots in Mesoporous CeO2 for Photocatalytic CO2 Reduction: Structure Regulation and Built-in Electric Field Construction

Halide perovskites have shown great promise in photocatalytic CO2 conversion. However, their practical application is seriously hindered by severe charge recombination and inadequate adsorption/activation toward CO2 molecules. Herein, the space-confined growth of lead-free Cs2CuBr4 perovskite nanodots in mesoporous CeO2 was realized by a facile impregnation approach. An outstanding CO2 photoreduction performance is achieved by the optimum Cs2CuBr4/CeO2 heterojunction with CO and CH4 yields of 271.56 and 83.28 μmol g–1, respectively. Experimental characterizations and theoretical calculations cooperatively validate the S-scheme charge transfer mechanism in the Cs2CuBr4/CeO2 heterojunction. The CO2 photoreduction pathway is also revealed by combining in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) and density functional theory (DFT) calculations. This study provides useful guidance for the design of high-performance halide perovskite/mesoporous material heterostructure photocatalysts for artificial photosynthesis.