Synthesis and characterization of reduced graphene oxide–V2O5 nanocomposite for enhanced photocatalytic activity under different types of irradiation

Abstract

Photocatalytic degradation of methylene blue with use of reduced graphene oxide (rGO)-V2O5 nanocomposites under mercury-lamp, visible-light, and UV-light irradiation is investigated. Graphene oxide (GO) synthesized by a modified Hummer's method was reduced to rGO by chemical reduction with hydrazine hydrate. In addition, V2O5 nanorods and rGO-V2O5 nanocomposite were synthesized by a hydrothermal method. The samples prepared were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, UV–vis diffuse reflectance spectra, photoluminescence, and UV–vis absorption analysis. XRD analysis of rGO-V2O5 nanocomposite indicated characteristic peaks of GO and V2O5 nanorods. Different nanostructure morphologies of the samples were revealed by FE-SEM. Raman spectroscopy showed the coexistence of rGO characteristic peaks and different vibrational modes of V2O5. The band gap of V2O5 nanorods (2.26 eV) reduced after graphene decoration to 1.60 eV for rGO-V2O5 nanocomposite. Moreover, unlike V2O5 nanorods, strong photoluminescence quenching in the visible range of the spectrum for rGO-V2O5 nanocomposite was observed. Detailed UV–vis absorption spectroscopy analysis revealed gradual degradation of methylene blue with increasing time under illumination with different irradiation sources. The maximum degradation efficiency for decolorizing methylene blue solution by rGO-V2O5 nanocomposites is about 85% after 255 min of illumination with a mercury lamp.