Effect of preparation parameters on photoactivity of BiVO₄ by hydrothermal method

Bismuth vanadate (BiVO₄) was synthesized from a mixture of aqueous Bi(NO₃)₃ and NH₄VO₃ solutions by using hydrothermal method. Via conducting the orthogonal experiments and single-factor experiments, the best synthetic parameters were determined. The physical and photophysical properties of the as-obtained samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV-Vis diffusion reflectance spectroscopy (UV-Vis). The result showed that the best experimental parameters of monoclinic BiVO₄ were pH = 7, T = 195 °C, and t = 6 h. The catalytic performance of BiVO₄ was evaluated by reducing carbon dioxide to methane under visible light irradiation. It was found that the methane production reached 145 μg/g-cat after 5 h irradiation with the catalyst dosage of 0.15 g in 200 mL mixed solution of 0.1 M NaOH and 0.1 M Na₂SO₃.