Preparation of water-dispersible TiO2 nanoparticles from titanium tetrachloride using urea hydrogen peroxide as an oxygen donor

Abstract

TiO2 nanoparticles were prepared from titanium tetrachloride (TiCl4) in CH2Cl2 at 80 °C for 30 h, 42 h and 70 h using urea hydrogen peroxide (UHP) as an oxygen donor with a TiCl 4: UHP molar ratio of 1 : 2. The XRD patterns and Raman spectroscopy results showed that the products consisted of anatase TiO2. IR and solid-state 13C NMR with cross polarization and magic angle spinning techniques revealed the presence of urea. TEM observation revealed that the products prepared by the reactions for 30 and 42 h consisted of water-dispersible spheroid nanoparticles with a long axis of ~5 nm, while an aggregation of nanoparticles was evident upon reaction for 70 h. Thermogravimetry, inductively-coupled plasma emission spectrometry and CHN analysis showed that the amount of urea increases in the following order: TiO2-42h, TiO2-70h, TiO2-30h. The photocatalytic activity of the products dispersible in water (TiO 2-30h and TiO2-42h) was estimated based on the degradation behaviour of methylene blue, and TiO2-42h showed higher photocatalytic activity than TiO2-30h. It is proposed that TiCl 4 was directly oxidized by UHP to form anatase TiO2 in the early stage of the process. © 2013 The Royal Society of Chemistry.