Hydrothermal Synthesis and Visible-light Photocatalytic Property of Monoclinic BiVO_4

Visible light photocatalyst BiVO4 with a monoclinic microstructure was synthesized by hydrothermal method at 140℃.Effects of hydrothermal temperature,hydrothermal time and pH value of synthetic solution on the microstructure and photocatalytic property of BiVO4 were studied.The products were characterized by X-ray diffractometry(XRD),scanning electron microscopy(SEM),BET specific surface area and ultraviolet-visible(UV-Vis) absorption measurements.Results show that the obtained BiVO4 presents hollow-microtube framework.It was favourable to form monoclinic BiVO4 by increasing the hydrothermal temperature,raising the pH value of the solution and prolonging the reaction time.So the optimum reaction conditions for fabricating monoclinic BiVO4 was determined as following: adjusting the pH value of synthetic solution to 9,controlling hydrothermal temperature at 140℃ and fixing the hydrothermal time to 6 h.The photocatalytic activity and reaction mechanism of BiVO4 was tested by photodecompostion of methylene blue under visible light illumination.Results indicate that the BiVO4 synthesized under the optimal conditions possesses quite good visible light photocatalytic activity.Meanwhile,increasing the pH value of the degradation systems is beneficial to improve photocatalytic capability of BiVO4 because of its enhancing absorption capacity and using efficiency of activated electron.