Selective synthesis of TiO2 nanocrystals with morphology control with the microwave-solvothermal method

In this paper, a method to synthesize anatase TiO2 nanorods by hydrolysis of titanium (IV) isopropoxide (TTIP) in the presence of benzyl alcohol and acetic acid, at 210 oC was tested. The novelty of the present approach relies on the test of shape-controlled synthesis of anatase TiO2 nanocrystals, via microwave-solvothermal method in 45 min. The different TiO2 nanocrystals were obtained tuning the TTIP-acetic acid ratio under optimized synthetic conditions and were characterized in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Micro Raman (together with microphotoluminescence) and FT-IR spectroscopies. Acetic acid coordinated on the nanocrystal surface was removed by the reduction of its carboxyl group via a “super-hydride reaction”, and the photocatalytic activity of bare TiO2 nanocrystals, under visible light irradiation, was also evaluated: the best performing TiO2 anatase nanocrystals exhibited a discrete photoactivity, completely degrading a Rhodamine B solution in five hours.