Low temperature synthesis of anatase TiO2 nanocrystals using an organic-inorganic gel precursor

Abstract

The purpose of this research was to establish a novel approach to synthesize nano-crystalline anatase TiO2 powder through a low temperature solution process and extracting TiO2 from the solution via freeze-drying procedure. The amorphous TiO2 precursors were first prepared using an aqueous TiCl4 solution and N, N-dimethylformamide as a TiO2 structure directing agent at 40 °C. The freeze-drying treatment of the DMF-derived amorphous Ti(IV) gel precursors produced organic–inorganic hybrids, including crystallized tiny TiO2 particles. The size, shape, and crystal phase of the TiO2 particles were determined by using transmission electron microscopy and X-ray diffraction. Most notably, anatase TiO2 nanocrystals were successfully obtained at less than near-room temperature. Furthermore, a sintering process of the gel precursors at 500 °C produced anatase TiO2 nanoparticles with three-dimensional network morphology. The resulting nanoparticles were found to have approximate grain sizes of 30–50 nm, with the organic-inorganic gel supporting the crystallization as a template.