V2O5/BiVO4 nanowires with enhanced photocatalytic activity for degradation of methylene blue

In this work, the Na5V12O32 nanowires on Ti foil are prepared by a hydrothermal method, and then the V2O5/ BiVO4 nanowires are fabricated via a controllable ion-exchange and calcination methods using the Na5V12O32 nanowires as precursor. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, etc. After the ion-exchange process, nanosheets are found on the surface of the nanowires, which can be transformed to nanoparticles after calcination at 450 celcius in air. Further, the pure BiVO4 is obtained by dissolving the V2O5 in the V2O5/BiVO4. By using V2O5/BiVO4 and BiVO4 nanowires as photocatalysts, the photocatalytic degradation rates of methylene blue were 99.51% and 75.10%, respectively, after 90 min visible light irradiation. After three cycles, the degradation rate of the V2O5/BiVO4 maintains 95.28%. From the results of transient photocurrent responses, photocurrent density-potential, electrochemical impedance spectroscopy, and Mott-Schottky measurements, the V2O5/BiVO4 nanowires exhibit a higher photogenerated charge carrier separation efficiency than that of the BiVO4, and the superoxide anion radical (& BULL;O2-) serves as the principal active species in the photocatalytic reaction.