(600ck) Hydrothermal Synthesis of Graphene/Fe3+-Doped TiO2 Nanowire Composites with Enhanced Photocatalytic Activity Under Visible Light Irradiation

TiO₂ is one of the most widely investigated semiconducting metal oxides that exhibits photocatalytic activity and is used in a wide range of applications. However, with its 3.2 eV electronic band gap, TiO₂ is only sensitive to the light wavelengths below ∼380 nm which belong to the UV range. Besides, the photogenerated electron−hole pairs, which are mainly responsible for the photocatalytic activity, have faster recombination rates than the rate of chemical interaction between TiO₂ and adsorbed pollutants, reducing the photocatalytic efficiency. To enhance photocatalytic activity of TiO₂, many methods have been employed, such as ion doping, graphene incorporating and so on.

In this study, the hydrothermal method was employed to synthesize Fe³⁺ −doped TiO₂ nanowires (FeNW) and then fabricate graphene/Fe³⁺−Doped TiO₂ nanowire nanocomposite (GFeNW). Graphene oxide (GO) reduction to graphene and hybridization between FeNWs and graphene by forming chemical bonding was achieved in a one-step hydrothermal process. Graphene/TiO₂ nanoparticle  nanocomposite (GNP) and graphene/ TiO₂ nanowire nanocomposite (GNW) were also synthesized as controls. Photocatalytic performance and related properties of TiO₂ nanoparticle (NP), TiO₂ nanowires (NW), FeNW, GNP, GNW and GFeNW were comparatively studied. It was found that by incorporation of graphene, GNP, GNW and GFeNW have higher performance than their counterparts. It was also found that FeNWs and NWs, in comparison with NPs, have more uniform dispersion on graphene with less agglomeration, resulting in more direct contact between TiO₂ and graphene, and hence further improve electron−hole pair separation and transportation. The diffuse reflectance spectra and photocurrent properties of these composites indicated that Fe³⁺ doping could improve the response of TiO₂ nanowire under visible-light irradiation. The result reveals that the relative photocatalytic activity of GFeNW is highest of all.