Phase and morphology transformation from assembled hexagonal HTiOF3 prisms to {001} faceted TiO2 nanosheets

Abstract

A three-stage synthesis method was developed for the preparation of TiO₂ nanosheets with exposed {001} facets by a solvothermal process. The formation mechanism of the TiO₂ nanosheets was investigated by the variation of the solvothermal temperature and reaction time. In the three-stage synthesis process, assembled hexagonal HTiOF₃ prisms were produced in the first stage, and then the hexagonal HTiOF₃ prisms transformed gradually into cubic TiOF₂ in the second stage. Anatase TiO₂ nanosheets with exposed {001} facets are formed from cubic TiOF₂ after the third stage. The results reveal that the reaction time and temperature play important roles in controlling the transformation of the morphology and phase from the assembled hexagonal HTiOF₃ prisms into the TiO₂ nanosheets through cubic TiOF₂. In addition, compared with hexagonal TiO₂ prisms and cubic TiO₂ calcined from HTiOF₃ and TiOF₂, the TiO₂ nanosheets synthesized by the three-stage solvothermal strategy exhibited better photocatalytic performance. The finding of this work presents a distinctive formation mechanism of TiO₂via intermediates HTiOF₃ and TiOF₂ to obtain TiO₂ nanosheets with controllable morphologies and excellent properties.