Enlarging the application of potassium titanatenanowires as titanium source for preparation of TiO2nanostructures with tunable phases

Abstract

One-dimensional (1D) structured sodium titanate (Na-titanate) derived from the NaOH treatment of TiO₂ nanoparticles under highly basic conditions are widely used as precursors to prepare TiO₂ with various crystalline phases, shapes, sizes or exposed facets. However, potassium ions in the potassium titanate (K-titanate) structure couldn't be fully exchanged by protons, therefore only a few studies have been conducted on the preparation of pure TiO₂ from K-titanate precursor. In this paper, we report that K-titanate could be fully transferred to pure TiO₂ through hydrothermal reaction in acidic solution. As a result, pure phase and mixtures of four TiO₂ polymorphs (anatase, rutile, brookite, and TiO₂(B)) could be controllably obtained. The transformation mechanism from K-titanate to TiO₂ counterparts was proposed. In addition, the photocatalytic activities of TiO₂ nanocrystals with different crystalline-phase composition have been investigated, and the mixed-phase samples showed much higher photocatalytic activity than either of the pure component phases.