Hierarchical WO₃ hollow shells: Dendrite, sphere, dumbbell, and their photocatalytic properties

In this work, hierarchical WO₃ hollow shells: dendrites, spheres and dumbbells have been successfully synthesized by simply calcining the acid-treated PbWO₄ and SrWO₄ as precursors at 500°C for 2 h. These hollow structures were characterized using X-ray diffraction, scanning and transmission electron microscopies, Brunauer-Emmet-Teller surface area and diffuse reflectance spectroscopy, respectively. Possible formation mechanisms for hollow WO₃ shells consisted of tiny nanoplatelets were investigated in detail. Comparing with commercial WO₃ particles, all the obtained hollow shells with larger BET surface areas showed enhanced photocatalytic activities for the degradation of organic contaminants under visible light irradiation.