Preparation and visible light photocatalytic activity of Bi₂O₃/Bi₂WO₆ heterojunction photocatalysts

The Bi₂O₃ nanorods, flower-like Bi₂WO₆ and Bi₂O₃/Bi₂WO₆ heterojunction composites with the molar ratio of n_Bi:n_W from 2:1, 2.5:1, to 3:1 have been synthesized via one-step hydrothermal method and two-step hydrothermal method, respectively. The products are characterized by powder X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), and scanning electron microscopy (SEM). Photocatalytic experiments indicate that such Bi₂O₃/Bi₂WO₆ composite possesses higher photocatalytic activity for RhB degradation under visible-light irradiation in comparison with pure Bi₂O₃ and Bi₂WO₆. The enhancement of the photocatalytic activity of the Bi₂O₃/Bi₂WO₆ heterojunction catalysts can be ascribed to the reduced recombination of the photoexcited electrons and holes during the photocatalytic reaction. The effect of the molar ratio of n_Bi:n_W on the catalytic performance of the heterojunction catalysts was also investigated. And the optimal molar ratio of n_Bi:n_W is 2.5:1 which was synthesized by one-step hydrothermal method. (paper)