Solvothermal Synthesis of TiO2 Nanocrystal Colloids from Peroxotitanate Complex Solution and Their Photocatalytic Activities

TiO2 nanocrystal colloids with different shapes and sizes have been prepared from a peroxotitanate complex solution starting from titanium(IV) sulfate and hydrogen peroxide (H2O2) in water/alcohol media by a solvothermal process. The TiO2 nanocrystals were characterized by transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, FT-IR spectroscopy, zeta potential, and nitrogen adsorption. The TiO2 nanocrystal colloids prepared by a solvothermal process at 120 degrees C show a highly crystallized anatase phase. The particle sizes decreased with the increase of the alcohol/water ratio. The shapes of the particles have been controlled from the rodlike in pure water solvent to a rectangular shape in pure ethanol solvent. The photocatalytic activities of TiO2 nanocrystals were evaluated by the degradation of phenol. The photocatalytic activity of the anatase nanocrystal was closely related to the particle diameter. In addition, the possible growth mechanism of this anatase was illustrated.