Template-Free Synthesis of Monoclinic BiVO(4) with Porous Structure and Its High Photocatalytic Activity

Monoclinic BiVO(4) photocatalysts with porous structures were synthesized by a two-step approach without assistance of any templates. The as-prepared samples were characterized by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (DRS), photocurrent responses, and electrochemical impedance spectra (EIS). It is found that the as-prepared BiVO(4) samples had a porous structure with aperture diameter of 50–300 nm. Moreover, the BET specific surface area of the porous BiVO(4)-200 °C sample reaches up to 5.69 m(2)/g, which is much higher than that of the sample of BiVO(4) particles without porous structure. Furthermore, a possible formation mechanism of BiVO(4) with porous structure was proposed. With methylene blue (MB) as a model compound, the photocatalytic oxidation of organic contaminants in aqueous solution was investigated under visible light irradiation. It is found that the porous BiVO(4)-200 °C sample exhibits the best photocatalytic activity, and the photocatalytic rate constant is about three times of that of the sample of BiVO(4) particles without porous structure. In addition, the photocurrent responses and electrochemical impedance spectra strongly support this conclusion.