Amplified internal electric field of Cs2CuBr4@WO3-xS-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-xS-scheme heterojunction demonstrated outstanding photocatalytic CO2reduction performance, with the electron consumption rate(Relectron) up to 390.34 μmol g-1h-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, electron spin resonance(ESR), photo-irradiated Kelvin probe force microscopy(KPFM), and in-situ X-ray photoelectron spectroscopy(XPS). Finally, the CO2photoconversion route was explored in detail using in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) and DFT theoretical calculations.