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TiO2 Lattice (tio2 + lattice)
Selected AbstractsImproved-Performance Dye-Sensitized Solar Cells Using Nb-Doped TiO2 Electrodes: Efficient Electron Injection and TransferADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Xujie Lü Abstract Well-crystallized Nb-doped anatase TiO2 nanoparticles are prepared by a novel synthetic route and successfully used as the photoanode of dye-sensitized solar cells (DSSCs). The homogenous distribution of Nb in the TiO2 lattice is confirmed by scanning transmission electron microscopy (STEM) elemental mapping and line-scanning analyses. After Nb doping, the conductivity of the TiO2 powder increases, and its flat-band potential (Vfb) has a positive shift. The energy-conversion efficiency of a cell based on 5.0,mol% Nb-doped TiO2 is significantly better, by about 18.2%, compared to that of a cell based on undoped TiO2. The as-prepared Nb-doped TiO2 material is proven in detail to be a better photoanode material than pure TiO2, and this new synthetic approach using a water-soluble precursor provides a simple and versatile way to prepare excellent photoanode materials. [source] Application of ion beam techniques for preparation of metal ion-implanted TiO2 thin film photocatalyst available under visible light irradiation: metal ion-implantation and ionized cluster beam methodJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001Hiromi Yamashita Transparent TiO2 thin film photocatalysts have been prepared on silica glass plate by an ionized cluster beam (ICB) method. In order to improve the electronic properties of these photocatalysts, transition metal ions V+, Cr+, Mn+, Fe+) were implanted into the TiO2 thin films at high energy acceleration using an advanced metal ion-implantation technique. The combination of these ion beam techniques can allow us to prepare the TiO2 thin film photocatalysts which can work effectively under visible light (, > 450 nm) and/or solar light irradiation. The investigation using XAFS and ab initio molecular calculation suggests that the substitution of octahedrally coordinated Ti ions in TiO2 lattice with implanted metal ions is important to modify TiO2 to be able to adsorb visible light and operate under visible light irradiation. [source] Phonons and Raman spectra of lithiated titanate Li0.5TiO2PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 11 2004R. Baddour-Hadjean Abstract Raman spectra of the electrochemically lithiated TiO2 anatase evidence that Li intercalation induces complex spectral features in the high wavenumber range. These modes can be assigned to the stretching vibrations of Li-O valence bonds. Two theoretical approaches are used to describe the vibrations of Li atoms within the TiO2 lattice. First, the quantum-mechanical calculations of molecular clusters imitating the Li...TiO2 system, which showed formation of covalent Li-O bonds and allowed an estimation of their force constants. Second, the lattice dynamics simulation which enabled to predict the whole spectrum of Li-phonons and their interaction with TiO2 lattice vibrations. Complex structure of the observed Raman spectra is explained by multiplicity of the Li positions. This results in multiple Raman bands originated from the Li atom vibrations covering a wide frequency range from 450 up to 950 cm,1. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Heterometal Alkoxides as Precursors for the Preparation of Porous Fe, and Mn,TiO2 Photocatalysts with High EfficienciesCHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2008Xiao-Xin Zou Abstract Transition-metal-doped titanium glycolates (M,TG, with M=Fe, Mn), which are the first non-stoichiometric heterometal alkoxides, have been synthesised through a solvothermal doping approach. X-ray diffraction, UV/Vis diffuse reflectance and ESR spectroscopy revealed that the dopant ion (Fe3+ or Mn2+) is substituted for Ti4+ in the TG lattice. Fe3+ prolongs the crystallisation time of Fe,TG, whereas Mn2+ has a smaller effect on the crystallisation time in comparison with Fe3+. The as-synthesised M,TG materials were used directly as single-source precursors for the preparation of metal-doped titania (M,TiO2) through a simple thermal treatment process. The as-prepared M,TiO2 materials maintain the rod-like morphology of the precursors and possess a mesoporous structure with high crystallinity. It has been proved that the dopant ions are incorporated into the TiO2 lattice at the Ti4+ positions. The photocatalytic activities of the M,TiO2 materials obtained were evaluated by testing the degradation of phenol under UV irradiation. From the photocatalytic results, it was concluded that high crystallinity, a large surface area and appropriate transition-metal-doping are all beneficial to the enhancement of the photocatalytic performance of the doped TiO2 material. In addition, it was noted that in comparison with Mn,TiO2, Fe,TiO2 shows higher photocatalytic activity due to the better inhibition effect of Fe3+ on recombination of photogenerated electron,hole pairs. In contrast to the conventional nanosized TiO2 photocatalyst, the micrometre-sized M,TiO2 particles we obtained can be easily separated and recovered after the photocatalytic reactions. [source] | ||||||||||