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Nanocrystalline TiO2 has been intensively studied because of its outstanding properties for application in, for instance, photocatalysis and solar energy conversion. The hydrolysis of titanium compounds, such as titanium alkoxides or halides, has been frequently used to prepare nanosized TiO2. However, the rate of hydrolysis of titanium compounds is too quick to be easily controllable. Another disadvantage is that the product usually has too much surface OH, which leads to aggregation and low photocatalytic activity. To overcome these specific problems of aqueous systems, we have developed a novel and simple non-aqueous route for synthesizing nanocrystalline TiO2 and Pt, Au, Ag-TiO2 with high photocatalytic activity. The nanocrystalline TiO2 were obtained by pyrolysis of titanyl organic, which was synthesized from the reaction of titanium tetrabutoxide [Ti(OC4H9)4] with ethyl glycol. Pt, Au and Ag nanoparticles supported on the nanocrystalline TiO2 could also be easily prepared when the corresponding noble metal salt (K2PtCl6?H2O, HAuCl4?H2O or AgNO3) was included in the non-aqueous reaction system. By varying the reaction temperature, the reactant ratio, pyrolysis temperature and time, the particle size, surface area and crystal phase of the nanostructured TiO2 could be selectively tailored. XRD, NMR, FTIR, TG-DTA-MS and chemical elements analysis were used to determine the structure of the titanyl organic intermediate. The final products were characterized by XRD, TEM, HRTEM, FTIR, EDX, XPS, UV-Vis absorption spectra and SBET measurement. For selected conditions, the samples possess high photocatalytic activity in the liquid photocatalytic degradation of an azo dye, active yellow XRG, which can be partly attributed to the suitable amount of surface C and OH groups formed upon pyrolyzing the titanyl organic compound. Pt, Au and Ag nanoparticles have been shown to further enhance the photocatalytic activity. The detailed mechanism underlying this enhancement is currently under investigation. To this end, we employ hole-mask colloidal lithography to prepare noble metal nanoparticles of well-defined size and shape on a TiO2 support, and we study the influence of nanoparticle chemistry, size and shape on the photocatalytic activity. |