Crystal violet degradation over BiVO4 photocatalyst under visible light irradiation

Sigle phase scheelite-monoclinic BiVO4 materials with different morphologies were successfully fabricated via a facile hydrothermal process by controlling pH of the precursor. The photocatalytic properties of the as-prepared materials were assessed via the photodecomposition of crystal violet (CV) solution under a 60?W LED (Cree-L6) visible light irradiation. The Langmuir-Hinshelwood model was utilized to present kinetic behavior. The obtained BiVO4 exhibited a monoclinic crystalline structure and narrow bandgap energy (E-g = 2.3?2.6?eV), which were confirmed by the X-ray diffraction (XRD), Raman and UV-vis diffuse reflectance spectra (UV-vis DRS) results. From the scanning electron microscopy (SEM) results, BiVO4 morphologies could be facilely controlled by turning the pH value of the precursor. When pH = 0.3, the BiVO4 products showed spherical morphologies with particle sizes in the range of 1?5??m. Rod- and spherical like-BiVO4 products were obtained when the pH of the precursor was adjusted to 3. Moreover, BiVO4 with nanoparticles could be prepared under the pH of 5?7, whereas leaf-like morphologies could be achieved when pH = 9. The photocatalytic test showed that the adsorption equilibrium constant depended on the morphologies of the BiVO4 products and the reaction rate constant was reached the highest level at pH = 3. This outcome indicated that the enhanced performance of BiVO4 significantly depended on the morphologies of the BiVO4 products and the effective suppression of photo-excited electrons and holes.