Synthesis of titanium(IV) oxide of ultra-high photocatalytic activity: high-temperature hydrolysis of titanium alkoxides with water liberated homogeneously from solvent alcohols

Abstract

Thermal treatment of titanium(IV) alkoxides dissolved in alcohols at temperature of 523–573 K under autogenous pressure yielded microcrystalline anatase titanium(IV) oxide (TiO 2) with diameter of 11–31 nm and surface area of 42–138 m 2 g −1. Similar treatment in hydrocarbons such as toluene gave no solid products, indicating that both hydrolysis of alkoxides with water liberated homogeneously from solvent alcohols and crystallization of anatase phase occurred simultaneously. These TiO 2's were thermally stable, e.g., BET surface area of TiO 2 synthesized at 573 K, 63 m 2 g −1, was reduced only 30% (45 m 2 g −1) even by calcination at 973 K. Their photocatalytic activity was examined in mineralization of acetic acid in aqueous solutions under aerated conditions and dehydrogenation of 2-propanol under deaerated conditions; almost all the samples showed the activity more than twice higher than those of representative active photocatalysts, Degussa P-25 and Ishihara ST-01. The superior activity of the present TiO 2 photocatalysts was attributable to compatibility of high crystallinity and large surface area owing to the newly developed synthetic procedure.