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

The Bi₂O₃/Bi₂WO₆ heterojunction photocatalysts were prepared by a two-step solvothermal process using Bi(NO₃)₃-ethylene glycol solution as Bi source. The catalysts were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and UV-vis diffuse reflection spectroscopy. The heterostructure catalysts are composed of Bi₂O₃ nanoparticles as modifier and 3D Bi₂WO₆ microspheres as substrate. Bi₂O₃ nanoparticles with diameters of about 10-15 nm are tightly grown on the lateral surface of the Bi₂WO₆ microspheres. The hierarchical Bi₂O₃/Bi₂WO₆ microspheres exhibit higher photocatalytic activity than the single phase Bi₂WO₆ or Bi₂O₃ for the degradation of rhodamine B under visible light illumination (λ>420 nm). The enhancement of the photocatalytic activity of the Bi₂O₃/Bi₂WO₆ heterojunction catalysts can be ascribed to their improved light absorption property and the reduced recombination of the photoexcited electrons and holes during the photocatalytic reaction. The effect of loading amount of Bi₂O₃ on the catalytic performance of the heterojunction catalysts was also investigated and the optimal content of Bi₂O₃ is 3 wt%. The Bi₂O₃/Bi₂WO₆ heterojunction photocatalysts are essentially stable during the photocatalytic process.