Synthesis of Au-decorated WO₃ nanoplates for simultaneous oxidation of RhB and reduction of Cr(VI) under visible light irradiation

Tungsten oxide (WO3) nanoplates were synthesized by a simple chemical precipitation technique. These nanoplates were decorated by Au nanoparticles via photoreduction route. The obtained samples were characterized by field emission scanning electron microscopy, X-ray diffractometry and UV-vis diffuse reflectance spectroscopy to investigate their morphological, structural and optical properties. The SEM images show the plate morphology with the size in the range of 50-150 nm, their thickness approximate to 10 nm; spherical-like Au nanoparticles approximate to 20 nm were attached to the surface of the WO3 plates. These materials were applied for the simultaneous photocatalytic degradation of Rhodamine B (RhB) and Cr(VI) under visible light. Due to the efficient separation of photoinduced charge carriers and the enhanced visible light absorption ability, the photocatalytic performance of Au-decorated WO3 nanoplates was higher. The main active species responsible for the photodegradation reactions were identified by different scavengers and a photocatalytic mechanism was proposed. This work represents that WO3 nanoplates are a promising candidate for the degradation of organic and inorganic pollutants from the industrial wastewater under sun light exposure.