A simple way to synthesize anatase with high thermal stability

A simple and cost-effective method was proposed to synthesize nano-crystallized pure anatase titanium dioxide (TiO₂) photocatalysts with a high thermal stability. The initial TiCl₄ was reacted with a NaOH aqueous solution to form an amorphous sodium titanate, which was then transformed into an amorphous titanium dioxide hydrate through the replacement of Na⁺ by H⁺ using a HCl aqueous solution. After annealing, the pure nano-crystallized anatase TiO₂ particles possessed a high thermal stability up to 900 °C. The high concentration of NaOH aqueous solution played an important role in preventing the precipitation of rutile TiO₂ during hydrolysis process and promoting the formation of the nano-crystallized anatase TiO₂. Samples calcined at 800 °C exhibited a significantly higher repeatable photocatalytic activity compared to the standard commercial photocatalyst P25 for the degradation of Rhodamine B in an aqueous suspension. This could be attributed to the synergistic effect of high crystallinity and mesoporous structure. The method is very simple, template-free, and cost effective, which makes it potential for the large-scale production.