Novel Magnetically Separable BiVO4/Fe3O4 Photocatalyst: Synthesis and Photocatalytic Performance under Visible-light Irradiation

Novel magnetically separable BiVO4/Fe3O4 visible-light-driven photocatalysts were successfully fabricated, in which Fe3O4 was coated on the surface of BiVO4 particles. The samples were characterized by means of XRD, SEM, EDS, UV-vis DRS, XPS, PL, FT-IR techniques. The results showed that the photocatalytic activity of BiVO4/Fe3O4 photocatalysts under visible-light illumination was higher than that of pure BiVO4 owing to the narrow band gap energy and delayed electron-hole recombination. Moreover, the mass fraction of Fe3O4 had considerable effect on the photocatalytic activity of BiVO4/Fe3O4. Among them, BiVO4/30% Fe3O4 composite exhibited superior activity, which made the degradation rate of Acid Red B reach to 97.6% after 40 min visible-light illumination. The degradation reaction accorded with first-order reaction kinetics equation. The rate constant of dye degradation reaction using BiVO4/30% Fe3O4 as photocatalyst was about 2.19 times of pure BiVO4. Furthermore, a photocatalytic degradation mechanism was proposed on the basis of IR, XRD and PL analysis, and the introduction of the scavengers for the reactive species. More importantly, the magnetic properties of BiVO4/Fe3O4 composite were measured and its reusability was also investigated after five successive runs applying an external magnetic field.