Novel BiSbO4/BiOBr nanoarchitecture with enhanced visible-light driven photocatalytic performance: Oxygen-induced pathway of activation and mechanism unveiling

Hetero-structured photocatalysts are known to accelerate the separation and migration of photo-induced carriers. In this study, we propose a novel BiSbO₄/BiOBr hetero-structured nanocomposite with enhanced molecular oxygen activation property. The formation of heterojunctions in the synthesized catalyst is confirmed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses. Based on photoluminescence spectra (PL), time-resolved transient decay photoluminescence spectra, and photoelectrochemical tests, it was shown that photo-induced electron transfer in BiSbO₄/BiOBr nanocomposites is faster than in pure BiSbO₄ or BiOBr. The accelerated migration of electrons promotes the activation of molecular oxygen and ultimately, enhances the degradation of Rhodamine B (RhB). Density function theory (DFT) calculations and electron spin resonance (ESR) tests indicate that the photo-induced electrons flow from BiOBr to BiSbO₄, leading to faster separation of photo-generated electron-hole pairs and further production of superoxide radicals. Liquid chromatography mass spectrometry (LC-MS) analyses were also conducted in order to identify the intermediates of RhB degradation. Knowing that the photocatalytic reaction is activated by an oxygen-induced pathway, it is possible to propose a mechanism for the degradation of RhB based on the identified intermediates.