Preparation and modification of hierarchical nanostructured Bi₂WO₆ with high visible light-induced photocatalytic activity

Hierarchical nanostructured Bi₂WO₆ micro-clews were synthesized by a solvothermal process with mixed solvents and formaldehyde. The hierarchical Bi₂WO₆ micro-clews, with an average diameter of ca. 1.0 µm, consisted of nano-sheets assembled in a special fashion and the formation process mainly went through an Ostwald ripening-anisotropic growth and self-assembling process. The Bi₂WO₆ micro-clews were further modified by Bi₂O₃ to fabricate heterojunction photocatalysts, where Bi₂O₃ nanoparticles were uniformly assembled on the surface of Bi₂WO₆ nano-sheets. Compared with pure Bi₂WO₆ and Bi₂O₃, the composite photocatalyst exhibits higher photocatalytic activity for the degradation of rhodamine B under visible light. On the basis of characterization by x-ray diffraction, photoluminescence and UV–vis diffuse reflectance spectroscopies, a mechanism was proposed to account for the enhanced photocatalytic activity of the Bi₂O₃/Bi₂WO₆ heterojunction.