Influence of Applied Potential on Titanium Oxide Nanotube Growth

The effect of applied potential on the morphology, growth efficiency, and composition of self-organized titanium oxide nanotubes, generated in /glycerol electrolyte, has been examined by electron microscopy, Rutherford backscattering spectroscopy, and nuclear reaction analysis. A linear increase in nanotube diameter, length, and wall thickness, with increasing applied potential is evident up to , whereas the growth efficiency decreases with increase of the applied potential. Due to the semiconductive properties of the titanium oxide, at potentials above some of the oxygen anions migrating across the barrier layer lose electrons and generate oxygen gas within the oxide. This results in a morphological transition above , characterized by the degeneration of nanotube geometry and uniformity, and the appearance of oxygen-filled voids within the barrier layer and nanotubes walls.