Synthesis and photocatalytic properties of sunlight‐responsive BiOBr–CoWO4 heterostructured nanocomposites

Abstract

AbstractEfficient sunlight‐responsive BiOBr–CoWO4 heterostructured nanocomposite photocatalysts were prepared via a chemical precipitation route at 100°C in 4 hours. The prepared BiOBr–CoWO4 heterostructures were characterized for phase identification, chemical composition, surface morphology, optical properties and surface area using various techniques. The X‐ray diffraction pattern of the BiOBr–CoWO4 nanocomposite was composed of diffraction peaks equivalent to both the tetragonal phase of BiOBr and the monoclinic phase of CoWO4 nanoparticles. X‐ray photoelectron spectral study of the BiOBr–CoWO4 nanocomposite revealed orbitals of both BiOBr and CoWO4 compounds. Transmission electron microscopy images revealed that spherical particles of CoWO4 (20–25 nm) were dispersed on the surface of BiOBr. UV–visible–near‐infrared spectral study of the BiOBr–CoWO4 nanocomposite showed good visible‐light absorption. Among the manufactured materials, BiOBr–CoWO4‐2 nanocomposite showed better charge carrier separation efficiency, as demonstrated by photoluminescence and time‐resolved fluorescence. To study the practical utility of the prepared materials, their photocatalytic capability was examined for the degradation of rhodamine B (RhB) aqueous solution under sunlight irradiation. The photodegradation results showed that BiOBr–CoWO4‐2 nanocomposite degraded 98.69% RhB solution and the degradation constant was 0.067 min−1, which was 5.6 and 22.5 times larger than that of pure BiOBr and CoWO4 nanoparticles, respectively, after 60 minutes of sunlight irradiation. The superior photoactivity was facilitated by electron–hole pair separation and transfer driven by the heterostructure interface between BiOBr particles and CoWO4 nanoparticles. The removal of RhB was initiated by photogenerated h+, O2•−and •OH reactive species based on the scavenger effect.