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.

Automated summary

Single phase scheelite-monoclinic BiVO4 materials with different morphologies were successfully synthesized via a hydrothermal method by controlling the pH of the precursor. The photocatalytic performance of the materials was evaluated, showing that the structure and bandgap energy of BiVO4 were influenced by the pH value. The study demonstrated that the morphologies of BiVO4 products played a significant role in enhancing the photocatalytic activity.