Facile preparation of flower-like Bi₂WO₆/CdS heterostructured photocatalyst with enhanced visible-light-driven photocatalytic activity for Cr(VI) reduction

Visible-light-driven CdS loaded flower-like Bi₂WO₆ (Bi₂WO₆/CdS) heterostructured photocatalyst with surface-enrich CdS nanoparticles were prepared successfully by using a facile two-step method. The as-prepared photocatalyst was characterized by X-ray diffraction, scanning electron microscopy, and UV–Vis diffuse reflectance spectrum. The band gaps of the samples were estimated based on diffuse reflectance spectrum results. The as-prepared Bi₂WO₆/CdS heterostructured photocatalyst was used as catalysts in reduction of Cr(VI) to Cr(III) under visible light irradiation, and enhanced photocatalytic activities were observed as compared to pure flower-like Bi₂WO₆ and CdS nanoparticles. The origin of the excellent performance of the catalyst as well as the mechanism of photoreduction was discussed. Effective electron–hole separation and variation of band gap due to the formation of type II heterostructure is believed to be responsible to the much improved reaction rate.

Flower-like Bi₂WO₆/CdS heterostructures was used to photoreduce toxic Cr(VI) to Cr(III) under visible light irradiation. 99% reduction of Cr(VI) could be reached within 10 min. It is found that the heterogenization favors the facilitated interfacial charge transfer and inhibited electron–hole recombination.