Abstract: V₂O₅·xH₂O-BiVO₄ composite photocatalysts were synthesized using monoclinic V₂O₅·xH₂O nanowires as a precursor under mild conditions. To determine the synthesis-time-dependent phase content, morphology, and photocatalytic performance of the products, three typical V₂O₅·xH₂O-BiVO₄ samples were obtained at 6, 12, and 24 h. These samples were investigated using X-ray diffraction, fieldemission scanning electron microscopy, UV-visible diffusion reflectance spectroscopy, and a photocatalytic property test. The results indicate that the V₂O₅·xH₂O-BiVO₄ nanocomposites are composed of V₂O₅·xH₂O nanowires and BiVO₄ nanocrystals. As the reaction time was extended, the amount of V₂O₅·xH₂O nanowires decreased gradually and that of the BiVO₄ nanocrystals increased in the composite. The results of photocatalytic performance indicated that the V₂O₅·xH₂O-BiVO₄ composite photocatalysts exhibited enhanced photocatalytic efficiency for the degradation of methylene blue (MB) under visible-light irradiation (λ>400 nm). The V₂O₅·xH₂O-BiVO₄ sample obtained at 12 h exhibited the best photocatalytic activity, which is probably because of the appropriate proportion of components and the special microstructures of the sample that were favorable for a synergistic effect between the two photocatalysis mechanisms involving the excitation of the semiconductor and the excitation of the dye, respectively.

Key words: Composite photocatalyst, Chemical synthesis, Characterization, Photodegradation, Organic dye