Hydrothermal preparation and photocatalytic properties ofquantum size TiO_2 nanoparticles

Anatase TiO_2 nanoparticles were prepared by hydreothermal synthesis method with titanium n-butoxide and ethanol as initial reagents. The average grain size of the anatase TiO 2 nanoparticles varied from 4~10()nm. Study of the dependence of photocatalytic property on the nanoparticle size and fluorescence spectrascopy show that the photocatalytic activities of the TiO 2 nanoparticles with average grain sizes of 8～9 nm are better than those of other sizes. With the surface activity of nanosized titanium dioxide increasing, the hydroxyl groups increase in grain surfaces. The obtained surface hydroxyl groups are abundant to facilitate the recombination of electron and hole and led to the decreasing photocatalytic activity of the nanoparticles. The fluorescence emission peak positions don't shift when the sizes of titanium dioxide change. The intensities of fluorescence emission spectra are not in proportion to the photocatalytic activities of titanium dioxide nanoparticles.