Investigation on the electrochemical properties of TiO2 nanotubes prepared by anodic oxidation

A new type TiO₂ nanotubes (TiO₂-NTs) were fabricated by forming nanotube-like TiO₂ film on a Ti sheet in anodic oxidation processes. The micro-morphology and phase structure of it was analyzed by FE-SEM and XRD, respectively. The average outer diameters of these nanotubes rang from 140 to 160 nm. The evidences from the electrochemical station indicated that the TiO₂-NTs had flat and wide potential window. Cyclic voltammetry of Fe²⁺ was conducted in 0.5 M KCl. A stable, quasi-reversible voltammetric response is seen for Fe at the TiO₂-NTs electrode, and the anodic and the cathodic peak potentials were 0.675 and -0.329 V vs. saturated calomel electrode at a scan rate of 0.05 V s^-1, respectively. Both anodic and cathodic peak currents depended linearly on the square root of the scan rate over the range of 0.025-0.2 V s^-1, which suggested that the process of the electrode reactions was diffusion-controlled. The photoelectrocatalytic experiments showed the high photoelectrocatalytic properties of TiO₂-NTs arrays electrode under visible light.