Electrochemical Impedance Spectroscopy as a Method of Differential Characterization of Electrical Behavior of Self-assembled TiO2 NTS

Nanotube (NTs) arrays of TiO2 have received great attention in various areas, such as gas-sensing, photocatalysis, solar energy conversion, and orthopedic implantation. Therefore, particular attempts are carried out to fabricate vertically oriented TiO2 nanotube arrays by electrochemical anodization in order to improve its properties to meet the practical application requirements. In the present work, the semiconductor behavior of self-organized vertically oriented TiO2 nanotube fabricated by a controlled corrosion process of electrochemical anodization of titanium foil using a simple method of glycerol based electrolyte (containing 0.27 mol/L NH4F and H2O in volumetric ratio 1:1) were studied by Electrochemical Impedance Spectroscopy (EIS). Ordered high-aspect-ratio TiO2 nanotube arrays with an inner tube diameter of ca. 45 nm in average and a tube height of 1 μm were identified by scanning microscopy and atomic force microscopy. TiO2 NTs semiconductor behavior was compared to a smooth titanium sheet with a spontaneous passivating TiO2 coating. The results showed that it is possible to represent the interface Ti/TiO2 electrical behavior as well as surface and the base of the nanotube.