Wet-chemical preparation of TiO2-nanostructures using different solvents: Effect of CTAB concentration and tentative mechanism of particle formation

摘要： In this paper, TiO2 nanostructures (TiO2-NSs) were synthesized in a controlled way. The effects of the use of a surfactant, Cetyl trimethylammonium bromide (CTAB), and the nature of the solvent of synthesis (ethanol and toluene) on the characteristics of the final product were studied. For this, TiO2-NSs were characterized using IR spectroscopy, X-ray diffraction (XRD), Transmission and Scanning Electron Microscopy. The solid obtained, without heat treatment, presented an amorphous structure that crystallized when treated at 450 °C, giving anatase as crystalline phase, independent of the solvent of synthesis and the concentration of CTAB used. The size of the crystallite in the powders synthesized was 3-5 nm and was reduced on increasing CTAB concentration, regardless of the solvent used. Using ethanol, the primary particles had a spheroidal or needle type shape of nanometric size (<100 nm) and the agglomerates were spherical (1 to 5 μm), reducing in size on the addition of CTAB. On using toluene, irregular-shaped aggregates with acute edges were formed (10 to 20 μm), made up of primary particles nanometric (<100 nm) and with the presence of poros. Given the nature of the synthesis process, a mechanism was proposed to explain the formation of the TiO2-NSs.