Synthesis and growth mechanism of TiO2-coated SiO2 fine particles

TiO2-coated SiO2 fine particles were synthesized by the hydrolysis of tetraethylorthosilicate (TEOS) and tetraethylorthotitanate (TEOT) in order to investigate the growth mechanism of TiO2 particles coated on monodispersed silica seed particles using the semi-batch reactor. Firstly, SiO2 seed particles with narrow particle size distribution were prepared by controlled hydrolysis of TEOS solutions. Secondly, SiO2 seed particles were allowed to coat and grow by further addition of TEOT as a precursor of TiO2 particles. Nielsenʹs chronomal analysis and Overbeekʹs theory were applied to clarify the growth mechanism of TiO2 particles coated on silica seed particles. As a result, it was found that the particle growth mechanism was presumed to be a surface reaction in which the rate determining step was a first-order polynuclear-layer growth mechanism and the growth rate constant, kpwas about 2.95×10−6 cm s−1.