Colloidal TiO2 nanocrystals prepared from peroxotitanium complex solutions: Phase evolution from different precursors

Abstract We report the preparation of nanocrystalline anatase and rutile TiO 2 from aqueous peroxotitanium complex (PTC) solutions and their characterization by powder X-ray diffraction (XRD), infrared spectroscopy, and Raman spectroscopy. The phase evolution of TiO 2 prepared using PTC derived from different precursors, i.e., TiCl 4 and titanium tetraisopropoxide (TTIP), is related to the nature of the intermediate steps. Phase-pure nanoanatase was formed in PTC solution derived from TiCl 4 , while a mixture of minor anatase and dominant rutile were prepared from PTC when TTIP was used as precursor. On the other hand, in the case of calcining PTC powders in air, a pure anatase phase of TiO 2 was obtained, regardless of the precursor used. Thus, the formation and attachment of hydrated TiO 6 units or TiO 2 · x H 2 O under a different environment, especially pH, plays a critical role in determining the phase during the crystallization of TiO 2 .