Facile hydrothermal synthesis and photocatalytic activity of bismuth tungstate hierarchical hollow spheres with an ultrahigh surface area

Abstract

Bismuth tungstate has attracted great attention as a new photocatalyst working under visible irradiation. In this paper, we demonstrate a facile hydrothermal route for controllable synthesis of novel Bi₂WO₆ hierarchical hollow spheres with an ultrahigh specific surface area in the presence of poly(vinyl pyrrolidone) at a proper C₂H₅OH/CH₃COOH/H₂O volume ratio. The obtained products are systematically studied by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller (BET) and UV-vis absorption spectroscopy. It is shown that the Bi₂WO₆ hollow spheres are constructed of numerous nanoplates while the nanoplates consist of a great deal of nanoparticles. UV-vis spectrum is used to estimate the band gap energy (about 2.90 eV) of the Bi₂WO₆ hollow spheres. The ultrahigh BET specific surface area of ca. 45.0 m² g⁻¹ is displayed for the Bi₂WO₆ hierarchical hollow spheres, which is much higher than that for all the previously reported Bi₂WO₆ products. The Bi₂WO₆ hierarchical hollow spheres are displayed to possess superior photocatalytic activity in the photodegradation of rhodamine B (RhB) under visible light irradiation over other morphological products.