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      Bandgap widening of titania through semiconductor support interactions.

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          Abstract

          Silica-supported titania powders with 50, 36, 13 and 4 wt% of TiO2 (TiO2-50/SiO2, TiO2-36/SiO2, TiO2-13/SiO2 and TiO2-4/SiO2) were prepared by hydrolysis of TiCl4 in the presence of silica, followed by calcination at 500 degrees C. The formation of Ti-O-Si linkages was confirmed by diffuse reflectance infrared Fourier transform spectroscopy. Atomic force microscopy indicated the presence of titania crystals larger than 15 nm. All supported materials exhibited a blue-shift of the TiO2 absorption edge, which was attributed to an electronic semiconductor support interaction. Bandgap energies of TiO2-50/SiO2, TiO2-36/SiO2, TiO2-13/SiO2 and TiO(2)4/SiO2 were measured to be 3.28, 3.36, 3.40 and 3.42 eV, respectively, as compared to 3.15 eV for unsupported TiO2. From these values, and from the quasi-Fermi level of electrons, a high anodic shift of both the valence and the conduction band was estimated. X-ray photoelectron spectroscopy (XPS) measurements of oxygen 1s- and titanium 2p-binding energies confirmed the anodic shift of the band edges.

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          Author and article information

          Journal
          Chemphyschem
          Chemphyschem : a European journal of chemical physics and physical chemistry
          Wiley
          1439-4235
          1439-4235
          Apr 2005
          : 6
          : 4
          Affiliations
          [1 ] Institut für Anorganische Chemie II, Universität Erlangen-Nürnberg, 91058 Erlangen (Germany).
          Article
          10.1002/cphc.200400185
          15881588
          f3db0601-7b47-4a39-9b71-e2265208dce1
          History

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