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.