Solvothermally controllable synthesis of anatase TiO2 nanocrystals with dominant {001} facets and enhanced photocatalytic activity

Abstract

A new non-hydrolytic approach was developed to synthesize anatase TiO2 nanocrystals with dominant {001} facets by solvothermal alcoholysis of TiF4, which was relatively green since the direct use of HF was avoided and less HF released from alcoholysis. These TiO2 nanocrystals displayed uniform shape and could be easily controlled owing to the smooth alcoholysis process. Using tert-butanol as the initial alcohol source, the total surface area was 103 m2 g−1 with small crystal sizes around 23 nm. By changing different alcohols, both the percentage of exposed {001} facets and the particle size could be adjusted. The results show that alcohols play important roles in the present strategy (1) oxygen donor to provide mild condition for crystal growth and (2) assistant agent to stabilize F species for dominant {001} facets. In further application, the absolute surface area of the {001} facets, instead of total surface area, has become the most important factor for influencing the activity of TiO2 crystals under photocatalytic selective oxidation of toluene to benzaldehyde.