Annealing effect on structural and optical properties of hydrothermally synthesized TiO2 nanowires

Abstract

TiO2 nanowires (TiO2 NWs) were successfully synthesized in large amounts through the one step hydrothermal process in 10 M NaOH aqueous solution at 150 °C for 15 h followed by annealing at 300-800 °C for 2 h. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scan electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). The optical properties of TiO2 nanowires were characterized using UV-VIS-NIR Spectrophotometers. It was found that the TiO2 nanowires persist in the anatase phase even after annealing at 500 °C and that the morphology of the nanowires was maintained. At 800 °C, the nanowires transformed into a rod-like shapes with a rutile structure. The optical band gap of TiO2 nanowires was found to decrease when the annealing temperature increases. Copyright © 2014 American Scientific Publishers All rights reserved.