Amplified internal electric field of Cs2CuBr4@WO3− S-scheme heterojunction for efficient CO2 photoreduction

Heterojunction construction, especially S-scheme heterojunction, represents an efficient universal strategy to achieve high-performance photocatalytic materials. For further performance stimulation of these well-designed heterojunctions, modulating the interfacial internal electric field (IEF) to steer dynamic charge transfer represents a promising approach. Herein, we realized the precise regulation of Fermi level (EF) of the oxidation semiconductor (mesoporous WO3−x) by tailoring the concentration of oxygen vacancies (VO), maximizing the IEF intensity in Cs2CuBr4@WO3−x (CCB@WO3−x) S-scheme heterojunction. The augmented IEF affords a robust driving force for directional electron delivery, leading to boosted charge separation. Hence, the developed CCB@WO3−x S-scheme heterojunction demonstrated outstanding photocatalytic CO2 reduction performance, with the electron consumption rate (Relectron) up to 390.34 μmol g−1 h−1, which is 3.28 folds higher than that of pure CCB. An in-depth analysis of the S-scheme electron transfer mode was presented via theoretical investigations, ESR, photo-irradiated KPFM, and in-situ XPS. Finally, the CO2 photoconversion route was explored in detail using in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and DFT theoretical calculations.