Preparation of various composite TiO2/SiO2 ultrafine particles by vapor-phase hydrolysis

Ultrafine TiO2/SiO2 composite particles were prepared by vapor-phase simultaneous hydrolysis of titanium tetraisopropoxide (TTIP) and tetraethoxyorthosilicate (TEOS). The various modes of TiO2/SiO2 composite particles, including both core-shell and mixed-type structures, were prepared according to the methods of reactant mixing. They differed considerably in morphology, size, chemical composition, and crystal structure evolution by heat treatment. In a mixed-type composite of TiO2 and SiO2, SiO2 inhibited both the growth of the particles and the anatase-to-rutile transformation of TiO2.