Influence of preparation method on morphology and photocatalysis activity of nanostructured TiO2.

Supported TiO2 photocatalysts on aerosol silica were prepared by adsorption phase reaction technique (APRT) and impregnation method (IMP) under different water concentrations. Energy dispersive X-ray microanalysis indicated that Ti concentration in samples prepared by both methods increased with the content of water rising. There was a sharp increase in Ti content curve of APRT samples, while Ti concentration of IMP samples changed slowly. The grain size of TiO2 by APRT was below 6 nm and TiO2 particles dispersed uniformly on surface of silica. But the size of TiO2 by IMP was larger than 20 nm and the number of large particles increased rapidly when water concentration increased. The photocatalysis activity of as-prepared catalysts was characterized by methyl-orange photodegradation. The results showed that APRT photocatalysts had higher photocatalysis activity than IMP photocatalysts. Ti concentration and TiO2 crystalline form were two factors which affected photocatalysis activity the most. The grain size of TiO2 had little influence on photocatalysis activity, which might be counteracted by the decrease of anastase TiO2.