(519f) Preparation of Transition Metal Doped TiO2 Nanowires/Reduced Graphene Oxide Composites with Enhanced Photodegradation Performance

Visible light driven TiO₂ photocatalyst nanowire arrays doped with transition metal were anchored onto the surface of reduced graphene oxide (RGO) nanosheets by using a one-step hydrothermal method in this work. The samples were characterized by X-ray diffraction, UV-visible diffuse reflectance spectroscopy, X-ray photoelectron spectra, Scanning Electron Microscope, Transmission electron microscope, Raman spectroscopy and Fourier-transform infrared spectroscopy. The XRD results showed that the diffraction peaks could be ascribed to anatase TiO₂. Both the SEM and the TEM micrographs exhibited that the TiO₂ nanowires with an average diameter of ∼10 nm and length of a several hundred nm were anchored onto the RGO nanosheets. Raman spectroscopy and FTIR indicated that most of GO were reduced after hydrothermal treatment. The photocatalytic properties of the prepared catalysts were evaluated for the photodegradation of methylene blue (MB) under visible light irradiation. The results showed that the degradation rate could reach up to 92% in 100 min by employing the modified TiO₂ nanowires/RGO composites, while the degradation rate was not higher than 50 % in 100 min by employing others. Transition metal doped TiO₂ nanowires/RGO composites exhibited the highest photocatalytic activity in comparison to the mono-incorporated and pristine TiO₂ nanowires. This improvement was attributed to the synergistic effect between transition metal and RGO. On the one hand, transition metal substituted in the Ti site in the lattice for the formation of the doping energy level narrowing the band gap energy. On the other hand, the presence of RGO not only led to enhanced adsorption of MB because of π-π conjugation, but also enhanced the adsorption of visible light and promoted the transportation and separation of photogenerated electrons and holes.