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dThis work reports on the synthesis of Li-doped TiO 2 nanoparticles using the sol-gel process and solid-state sintering, and investigates their potential use as a photocatalyst for degradation under sunlight excitation of different organic model compounds in aqueous solution. The structure of the nanocrystals was examined by X-ray diffraction, UV-vis ground state diffuse reflectance absorption spectra and X-ray photoelectron emission spectroscopy. Results showed that samples prepared by sol-gel process and calcined at 400• C are composed of a mixture of anatase and rutile phases, in contrast to the one prepared by solid-state sintering, which exhibits an anatase phase with Li being involved in a spinel phase. The photocatalytic degradation of aqueous solutions of different aromatic compounds was successfully achieved under sunlight excitation in presence of Li-doped TiO 2 prepared via sol-gel process. It was shown that the calcination temperature and the preparation mode greatly affect the photocatalytic efficiency.

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Three different sol-gel routes were used in order to study the stability and the crystallinity of the ternary system Y 2 O 3 , Ti(OBu) 4 , Rb 2 CO 3 . Different techniques such as FTIR, 13 C NMR TGA, DTA and XRD were used to characterize xerogels and final products. Results demonstrated that using hexanoic acid during the sol step preparation influences structural changes in the precursor gel. The effect of heat treatment to eliminate the organic material from xerogels was investigated by thermal gravimetry and differential thermalanalysis. According to the ratio of acetic acid to hexanoic acid, the phase structure of TiO 2 , viz. anatase to rutile phase, could tailored. The photocatalytic activity of the prepared catalysts, under sunlight irradiation, was evaluated using 2-naphthol as a pollutant model. Results showed a great enhancement in the photocatalytic efficiency for doped TiO 2 sample prepared in the presence of 30acet-70hex.