BiOBr/NiO S‐Scheme Heterojunction Photocatalyst for CO2 Photoreduction

Artificial photosynthesis by CO 2 photoreduction is an ideal channel for mitigating the greenhouse effect and energy crises. Nevertheless, its efficiency is still low due to severe charge recombination and sluggish kinetics. Herein, an S‐scheme BiOBr/NiO heterojunction, composed of two kinds of p‐type semiconductors, exhibits enhanced CO 2 photoreduction activity. Enhanced light absorption and specific surface area are attributable to NiO nanosheets with hierarchical porous structures. Results from in situ irradiated X‐ray photoelectron spectroscopy and work function calculation manifest that the photoexcited electrons transfer from BiOBr to NiO via the S‐scheme mechanism. And charge separation and a strong redox ability are simultaneously realized. In situ diffuse reflectance infrared Fourier transform spectra unveil complex intermediates in CO 2 photoreduction. This work presents a novel understanding for the CO 2 photoreduction mechanism of S‐scheme heterojunctions built by p‐type semiconductors by integrating in situ monitoring techniques with density functional theory calculation.