Ultrafine single-crystal TiOF2 nanocubes with mesoporous structure, high activity and durability in visible light driven photocatalysis

Abstract

Single crystal TiOF₂ nanocubes assembled into a mesoporous structure were synthesized by alcoholysis of TiF₄ under solvothermal conditions, which displayed spectral response in the visible area owing to the intrinsic narrow energy band gap. Mechanism studies revealed that TiOF₂ was formed via consecutive hydrolysis reactions and the H₂O produced by condensation between two alcohols played a key role in determining the TiOF₂ crystal growth and its transformation to anatase TiO₂. The TiOF₂ nanocube size could be easily adjusted by changing either alcoholysis time, or solvothermal temperature, or alcohol kind owing to the different H₂O production rate and amount. The small-sized TiOF₂ nanocubes with large surface area exhibited high activity in photocatalytic degradation of Rhodamine B (RhB) and 4-chlorophenol (4-CP) owing to the enhanced adsorption for reactant molecules and the reduced photoelectron–hole recombination rate. Meanwhile, they also showed strong durability since the mesoporous structure enhanced the stability against either the phase transformation from TiOF₂ crystal to anatase TiO₂ or the agglomeration of TiOF₂ nanocubes.