Relation of photoluminescence and sunlight photocatalytic activities of pure V2O5 nanohollows and V2O5/RGO nanocomposites

Vanadium pentoxide (V2O5) nanospheres and nanohollows were fabricated by wet chemical reaction and hydrothermal methods. X-ray diffraction (XRD) and Raman spectroscopy reveal that the V2O5 nanostructures have an alpha-V2O5 phase with orthorhombic structure. Reduced graphene oxide (RGO) was mixed with pure V2O5 nanostructures to form V2O5/RGO nanocomposites. The composition of V2O5, RGO, and V4+ oxidation states was investigated by X-ray photoelectron spectroscopy (XPS). The presence of V4+ oxidation states due to oxygen vacancies in the V2O5 nanostructures leads to a wide range of absorption and direct photocatalytic activity under sunlight irradiation. The peak photoluminescence (PL) intensity is around 670 nm in the V2O5/RGO nanocomposites, which is much lower than that of pure V2O5. This seems to be evidence of facile electron transfer from V2O5 to RGO due to the strong adhesion of RGO with pores on the V2O5 surface. This leads to the enhancement of the sunlight photocatalytic activity of the V2O5/RGO nanocomposites. The relation between the separation, diffusion, recombination, and degradation of the electron-hole pairs in the V2O5 nanostructures and V2O5/RGO nanocomposite is discussed.