Strain‐Engineering of Mesoporous Cs3Bi2Br9/BiVO4 S‐Scheme Heterojunction for Efficient CO2 Photoreduction

Abstract Slow charge kinetics and unfavorable CO 2 adsorption/activation strongly inhibit CO 2 photoreduction. In this study, a strain‐engineered Cs 3 Bi 2 Br 9 /hierarchically porous BiVO 4 (s‐CBB/HP‐BVO) heterojunction with improved charge separation and tailored CO 2 adsorption/activation capability is developed. Density functional theory calculations suggest that the presence of tensile strain in Cs 3 Bi 2 Br 9 can significantly downshift the p‐band center of the active Bi atoms, which enhances the adsorption/activation of inert CO 2 . Meanwhile, in situ irradiation X‐ray photoelectron spectroscopy and electron spin resonance confirm that efficient charge transfer occurs in s‐CBB/HP‐BVO following an S‐scheme with built‐in electric field acceleration. Therefore, the well‐designed s‐CBB/HP‐BVO heterojunction exhibits a boosted photocatalytic activity, with a total electron consumption rate of 70.63 µmol g −1 h −1 , and 79.66% selectivity of CO production. Additionally, in situ diffuse reflectance infrared Fourier transform spectroscopy reveals that CO 2 photoreduction undergoes a formaldehyde‐mediated reaction process. This work provides insight into strain engineering to improve the photocatalytic performance of halide perovskite.