Preparation and characterization of TiO2 nanoparticles by two different precipitation methods

This paper describes the structural and photocatalytic studies of TiO2 nanoparticles prepared by two different precipitation methods using titanium tetrachloride (TiCl4) and titanium oxalate [Ti(C2O4)2] as raw materials for the first time. The samples were characterized by TG-DSC, XRD, TEM, EDS, SAED, UV–Vis, Raman, N2 adsorption-desorption isotherms, and XPS to investigate the effects of salt type and calcination temperature on the crystal structure, morphology, composition, energy band gap and photocatalytic activity of TiO2 nanoparticles. Results indicated that when TiCl4 was used as Ti source, the crystallization temperature of amorphous TiO2 to anatase TiO2 was as low as 250 °C, but it increased to ~450 °C when Ti(C2O4)2 was selected. Besides, TiCl4 was able to dynamically modify the crystalline structure of TiO2 nanoparticles from anatase into rutile after calcination at ~450 °C, however this temperature was increased to ~850 °C for Ti(C2O4)2. The optimal photocatalytic property of methyl orange (MO) degradation in two TiO2 systems was 99.08% and 38.6% with corresponding calcination temperatures of 450 °C and 550 °C, respectively, which was mainly correlated with the different crystal structure and crystallite size.