Structural and optical property studies of TiO2 nanotube arrays prepared by anodic oxidation

TiO2 nanotube arrays (NTs) have been prepared by anodic oxidation and the oxidation voltages are 20, 30, 40 and 50 V, respectively. Microstructure, chemical composition and optical property of the TiO2 NTs were investigated. XRD and Raman spectra analysis show that the good crystal performance of TiO2 NTs obtained at the above voltages. The obtained samples are mainly composed of morphology nanotube arrays and TiO2 NTs are emerged at lower oxidation voltages. The Ti and O surface atom ratio for the sample prepared at 30 V is estimated about 1:2.14. UV-Visible absorption spectra analyses indicate that absorption edge appears slight blue shift phenomenon when the oxidation voltage rises and the absorption intensity decreases at the same time. The calculated optical band gaps for all samples are close to the standard value 3.2 eV of TiO2.