Amplified internal electric field of Cs₂CuBr₄@WO_3-x 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 (E-F) of the oxidation semiconductor (mesoporous WO3-x) by tailoring the concentration of oxygen vacancies (V-O), 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 (R-electron) up to 390.34 mu mol 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, electron spin resonance (ESR), photo-irradiated Kelvin probe force microscopy (KPFM), and in-situ X-ray photoelectron spectroscopy (XPS). Finally, the CO2 photoconversion route was explored in detail using in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and DFT theoretical calculations. (c) 2024 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.