Reduced graphene oxide-modified Bi2WO6/BiOI composite for the effective photocatalytic removal of organic pollutants and molecular modeling of adsorption

In this study, reduced graphene oxide (rGO) with unique physicochemical, optical, and electrical properties was applied in a varying content to improve the photocatalytic performance of Bi2WO6/BiOI towards the degradation of colorless organic pollutants: acetaldehyde (AcH) and chloramphenicol (CAP) under visible light. The rGO/Bi2WO6/BiOI composites were characterized by means of X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, and nitrogen gas adsorption analysis. The prepared rGO/Bi2WO6/BiOI composite with 1 wt% rGO demonstrated a much higher photodegradation rate constant towards the degradation of AcH and CAP than its Bi2WO6/BiOI counterpart. Such enhancement can be explained by the synergistic effects of rGO in adsorbing AcH and CAP molecules, capturing photoinduced electrons, and forming an additional p-n heterojunction with n-type Bi2WO6. The adsorption affinities of AcH molecules in the gas phase and CAP molecules in aqueous solution to model rGO, BiOI (102) and Bi2WO6 (113) surfaces were studied by molecular modeling using a layer building tool that allows the generation of layered structures and interfaces. It was found that compared to Bi2WO6, rGO and BiOI show the increased adsorption of AcH and CAP+water molecules over the rGO/BiOI surface in the rGO/Bi2WO6/BiOI and rGO/BiOI composites. The enhanced photocatalytic activity demonstrated by the newly prepared rGO/Bi2WO6/BiOI composite makes it a potential candidate for use in environmental remediation processes.