Control of the crystal structure of titanium(IV) oxide by hydrothermal treatment of a titanate nanotube under acidic conditions

Abstract

Crystal transformation of a titanate nanotube (TNT) into titanium(IV) oxide (TiO₂) particles proceeded under various hydrothermal conditions with an inorganic acid. The contents of the crystal structure of TiO₂, i.e., anatase, rutile and brookite, and the particle shape were greatly influenced by the type and concentration of inorganic acid, hydrothermal duration and temperature. TiO₂ particles with larger contents of brookite structure (more than 0.9 of the relative fraction of the crystal structures) were obtained by 50 h of hydrothermal treatment with 2 mol dm⁻³ of perchloric acid at a hydrothermal temperature of 200 °C.