A facile hydrothermal method for the controllable synthesis of TiO2 nanocrystals with tunable shapes

Abstract

The controllable preparation of anatase TiO₂ nanocrystals with tunable shapes has drawn much attention recently. The general method used to prepare such nano-TiO₂ involves the use of HF as a surfactant. However, the use of HF should be avoided due to its high risk. Therefore, the development of facile and friendly methods to controllably synthesize anatase TiO₂ nanocrystals is important. In this research, instead of general titanium precursors, titanium peroxide sol was used as the raw material to synthesize anatase TiO₂ nanocrystals due to its high stability in water. Oleic acid and oleylamine were used as capping surfactants. A hydrothermal method, without the use of high risk HF, was developed to prepare uniform anatase TiO₂ nanocrystals with various shapes, which can be tuned from octahedral bipyramidal, to truncated octahedral bipyramidal, and then to nano-sheets. The ratio between {001} and {101} surfaces can be easily tuned by changing the amounts of oleic acid and oleylamine used. The photocatalytic activity of these anatase TiO₂ nanocrystals was also evaluated through crystal violet photo-degradation under UV light illumination. It was shown that the anatase TiO₂ nanocrystals can present a photocatalytic activity comparable to that of commercial P25.