The role of solution temperature in characteristics of TiO2 nanotube arrays prepared on Ti foil in acid solution

Abstract

The characteristics of TiO₂ nanotube arrays (TNTs) prepared on Ti foil in sulfuric acid solution that contains Cl⁻ under different temperatures are investigated by field emission scanning electron microscopy (FESEM), electrochemical impedance spectroscopy (EIS), Mott–Schottky measurement and Raman spectra. The solution temperature significantly affects the morphologies of TNTs, i.e., when solution temperature rises from −10 °C to 90 °C, the inner diameter of the nanotube increases and the barrier layer thickness decreases, and, as TNTs display n-type semiconductive properties, the donor density (N_D) and corrosion protection decrease. Two types (types I and II) of pulse temperature are used to fabricate TNTs, in which type I is firstly anodized at a low temperature for time t, and then increases to a high temperature. While for type II, the solution temperature order is opposite to that of type I. The N_D of TNTs in the case of type I is lower than N_D of TNTs in the case of type II. N_D decreases with the increased pulse step time for type I, while N_D increases with the increased pulse step time for type II.