Rapid synthesis of a TiO2 hollow microsphere assembly from hollow nanoparticles with enhanced photocatalytic activity

Abstract

A novel hierarchical anatase TiO₂ hollow microsphere (TiO₂-HMS) assembly synthesised from TiO₂ hollow nanoparticles (TiO₂-HNP), denoted TiO₂-HMS-HNP, was rapidly fabricated by a simple hydrothermal route in a Ti(SO₄)₂–NH₄F–H₂O₂ mixed solution at 180 °C for only 3 h. The influence of NH₄F and H₂O₂ on the formation of TiO₂-HMS-HNP was studied. A novel mechanism for the formation of TiO₂-HMS-HNP based on a H₂O₂-assisted fluoride-induced self-transformation (FIST) process is proposed. The prepared TiO₂-HMS-HNP showed much higher photocatalytic activity than TiO₂-HMS, when the activity was evaluated both by the photocatalytic degradation rate of brilliant red X-3B (an anionic azo dye) and by the rate of formation of photo-induced hydroxyl radicals (˙OH) under UV irradiation.