A facile solid phase reaction to prepare TiO2 mesocrystals with exposed {001} facets and high photocatalytic activity

Abstract

As one of the most widely investigated and used materials, TiO₂ is expected to play a leading role in helping solve environmental and energy issues. In this work, we developed a facile, greener and more controllable approach of preparing anatase TiO₂ mesocrystals with largely exposed {001} facets. This approach utilizes the solid–solid topotactic transformation of NH₄TiOF₃ to anatase TiO₂ and only needs a simple sintering process. In order to obtain the exposed {001} facets on the surfaces of final products, the sintering temperature must be between 700 °C and 900 °C. Temperatures below 700 °C lead to unexposed {001} facets. Temperatures above 900 °C lead to a mixed phase of anatase and rutile. The photocatalytic activity of the TiO₂ mesocrystals is much higher than that of the corresponding TiO₂ polycrystalline materials and comparable with that of commercially available P25. The exposed {001} facets are believed to play a very important role in the photocatalysis process.