Conditions for Titania(IV) Recrystallization from the η Modification to Anatase

Abstract

The effect of some sensitizers (methylene blue, methyl red, chlorophylls, coproporphyrin I, and hydrogen peroxide) on the transformation of η-TiO₂, which is an anatase precursor in titanyl sulfate hydrolysis, into anatase has been studied. A decrease in the average crystallite size and suppression of the transformation of η-TiO₂ into anatase is observed in the presence of methylene blue and methyl red organic dyes, as well as Ti(IV) peroxocomplexes,. The sample synthesized in the presence of 1 M H₂O₂ is characterized by the smallest crystallite sizes (2−4 nm) and the highest photocatalytic activity.