Nanocrystalline TiO2: Crystal Structure Controlled Synthesis via Low Temperature Hydrolysis Method and Surface Texture

Nanometer titanias in different crystal structures with high specific surface area have been prepared at low temperature by the hydrolysis of titanium(Ⅳ) chloride (TiCl4), titanium(Ⅳ) nitrate (Ti(NO3)4) or titanium(Ⅳ) sulfate (Ti(SO4)2) precursor under highly acidic condition. The phase composition, morphology and the specific surface area of nanometer titania powders were characterized by means of XRD, TEM and N2-adsorption measurements. It is found that, titania in pure rutile phase or anatase-rutile mixed phase or pure anatase phase could be synthesized at low temperature in liquid media through controlling the hydrolyzation conditions. The well-crystallized rutile TiO2 with small particle size and high specific surface (above 200 m^2•g^(-1)) was formed at temperature equal to or below 80℃, while the anatase TiO2 was formed at higher temperature in hydrochloric or nitric acid solution. But in sulfuric acid solution the crystal phase was always anatase at any temperatures and the BET surface area of the as-prepared anatase titania was all more than 300 m^2•g^(-1).