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

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 degrees 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 degrees 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. (C) 2020 Published by Elsevier B.V.