Constructing BiVO4/Graphene/TiO2 nanocomposite photoanode for photoelectrochemical conversion applications

BiVO4/Graphene/TiO2 as a novel nanocomposite photoanode was designed, synthesized and characterized for photoelectrochemical application. BiVO4/Graphene nanocomposite was initially synthesized by photocatalytic process and then, BiVO4/Graphene/TiO2 nanocomposite thin film was prepared by deposition of the BiVO4/Graphene solution onto the surface of sol-gel derived TiO2 thin film. Morphology, crystal structure, surface chemical composition and optical properties of the synthesized BiVO4/Graphene/TiO2 nanocomposite thin film were characterized and compared with the BiVO4/Graphene and pure TiO2 samples. Observations of scanning electron microscopy (SEM) images revealed that the surface of the TiO2 thin film was modified by the BiVO4/Graphene with high surface area. According to X-ray diffraction (XRD) analysis, formation of anatase and monoclinic phase was confirmed for crystalline structure of TiO2 and BiVO4, respectively. UV-visible absorption spectra of the samples showed that the absorption edge and intensity of the BiVO4/Graphene/TiO2 nanocomposite film were increased with respect to the TiO2 film. The BiVO4/Graphene/TiO2 nanocomposite photoanode yielded a photocurrent density of similar to 130A/m(2) as compared to 0.27 A/m(2) for the TiO2 at 0.8 V vs Ag/AgCl under UV-visible irradiation in similar condition. The improved photoelectrochemical activity is believed due to the enhanced light absorption and higher surface area of BiVO4/Graphene as well as better charge transfer of the photogenerated carriers at the BiVO4/Graphene/TiO2 interfaces via Graphene. (C) 2016 Elsevier B.V. All rights reserved.