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Abstract: Nitrogen (N)-doped TiO2 samples with high specific surface areas were directly prepared by heating the mixture of urea and TiO2, where the TiO2 was obtained with titanium tetrachloride as precursor. The absorption spectrum of the N-doped TiO2 shifted to wavelength up to 600nm with increasing urea contents. X-ray photoelectron spectroscopic measurements showed that the N presented in TiO2 was in the state of both molecularly chemisorbed N2 and substituted N. While both of them contribute to the response to visible light, the latter gave the prepared samples with hydrogen evolution under visible light. The apparent photocatalytic activity of water splitting demonstrated as high amount of H2 evolution was partly due to the phase transformation from anatase to rutile for the N-doped TiO2. [Copyright &y& Elsevier]

Abstract: TiO2 (P25)–graphene (P25–GR) hybrids were prepared via solvothermal reaction of graphene oxide and P25 using ethanol as solvent. The as-prepared P25–GR nanocomposites were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence emission spectroscopy and ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy. The results indicated that P25–GR nanocomposites possessed enhanced light absorption ability and charge separation efficiency. As photocatalysts, P25–GR hybrids were much better than the bare P25, when they were used in the hydrogen evolution from aqueous methanol solution under Xe-lamp illumination. A significant enhancement in the rate of hydrogen production was achieved through using P25–GR as photocatalysts, comparing to bare P25. The optimum mass ratio of GR to P25 in the hybrids was 0.5wt%. The higher mass ratio of GR in P25–GR would decrease the photocatalytic activity of P25. [Copyright &y& Elsevier]