Guan Qingfeng

Controllable Synthesis and Photocatalytic Activity of Spherical, Flowerlike and Threadlike Bismuth Vanadates

Spherical, flowerlike, and threadlike bismuth vanadates (BiVO4 ) were synthesized via a controllable hydrothermal method without using any surfactant or template. The optical and photocatalytic properties of the BiVO4 samples were investigated. The phase structures of the BiVO4 samples were observed by X-ray diffraction (XRD), which indicated that the as-prepared samples possessed monoclinic cells. Transmission electron microscope (TEM) observations showed that BiVO4 crystals with different morphologies were fabricated simply by manipulating the parameters of the hydrothermal reaction. On the basis of the structural analysis of samples obtained under different conditions, a possible mechanism for the formation of these distinct morphologies was proposed. UV-visible diffuse reflectance spectra (UV-Vis DRS) of the samples revealed that the band gaps of the BiVO4 photocatalysts were about 2.19-2.33 eV. The as-prepared BiVO4 photocatalysts exhibited higher photocatalytic activities toward the degradation of rhodamine B (RhB) under visible light irradiation (λ 420 nm) than commercial P25 TiO2 and traditional N-doped TiO2 (N-TiO2 ). Spherical BiVO4 showed the highest photocatalytic activity of the samples, decolorizing up to 100% of RhB upon visible light irradiation for 180 min. The reason for the different photocatalytic activities of the BiVO4 samples fabricated at different pH was systematically studied by considering their structure and morphology.