Space-Confined Growth of Cs 2 CuBr 4 Perovskite Nanodots in Mesoporous CeO 2 for Photocatalytic CO 2 Reduction: Structure Regulation and Built-in Electric Field Construction.

Halide perovskites have shown great promise in photocatalytic CO 2 conversion. However, their practical application is seriously hindered by severe charge recombination and inadequate adsorption/activation toward CO 2 molecules. Herein, the space-confined growth of lead-free Cs 2 CuBr 4 perovskite nanodots in mesoporous CeO 2 was realized by a facile impregnation approach. An outstanding CO 2 photoreduction performance is achieved by the optimum Cs 2 CuBr 4 /CeO 2 heterojunction with CO and CH 4 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 Cs 2 CuBr 4 /CeO 2 heterojunction. The CO 2 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.