Datensatz

Zusammenfassung

Single-phase titania nanomaterials were prepared by autoclaving titanium tetrachloride in acetone at 80 - 140 °C. Depending on the molar ratio of TiCl₄ to acetone (TiCl₄/Ac), TiO₂ materials with different phases and morphologies were obtained. When the TiCl₄ concentration was no higher than TiCl₄/Ac ) = 1/15, single-phase anatase TiO₂ nanocrystals in sizes ranging from 4 to 10 nm were prepared by tuning TiCl₄/Ac ratios from 1/90 to 1/15. However, when the TiCl₄ concentration was high enough (e.g., TiCl₄/Ac ≥1/10), single-phase rutile TiO₂ nanofibers were obtained selectively. The materials were characterized comprehensively using X-ray diffraction, transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, and nitrogen adsorption measurements. With the aid of GC/MS analysis of organic products in the liquid phase, it is shown that the controlled hydrolysis of TiCl₄ with water, which was in situ generated from the TiCl₄-catalyzed aldol condensation reactions of acetones, played an important role in the formation of the titania nanomaterials. Some of the organic condensates mayfunction to stabilize the phase and morphology of the materials. This mechanism was also supported by our success in using other ketones as alternatives to acetone in the synthesis.