Effect of Reaction Time on Structure, Morphology and Optical Energy Gap of TiO2 Nanorods Prepared by One-Step Hydrothermal Method

In this study, well-aligned rutile TiO2 nanorod arrays were grown on fluorinedoped tin oxide (FTO) substrates by a hydrothermal technique using TiCl4 as the titania precursor. The influence of hydrothermal reaction (growth) time on the change of nanostructure shape and size during the preparation of the nanorods was examined. The study investigated the characteristics of the prepared TiO2 nanorods using various analytical techniques, such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Raman spectroscopy, and UV-visible spectrophotometer. Diverse structures, morphologies, and optical band gaps of TiO2 nanorods were obtained by varying the hydrothermal reaction time at optimized growth factors such as growth temperature, precursor concentration, and acidity. The composition remained rutile, although the particle size and the average diameter of the nanorods changed with the growth time. It was observed that the absorption edge shifted to longer wavelengths (redshift), and the predicted band gap of TiO2 decreased as the growth time increased. Additionally, the rutile phase was confirmed through Raman spectroscopic analysis.