TiO₂ nanotube array films grown in DMSO/EtOH-based electrolyte: Anodization current response and solvation effect

This work report on the fabrication of titania nanotube array film anodized in a fluoride-based electrolyte mixture of dimethyl sulfoxide and ethanol. Optimization of the anodization parameters has been examined and reported in a 3D surface plot, with the achieved result that the improved nanotube length is up to six times, as using the similar conditions reported in the previous work (Ruan et al. 2005 J. Phys. Chem. B 109, 15754.) With a systematically designed experiment, we demonstrate the more insight into interaction and solvation effect in the anodization electrolyte, particularly elucidating how electrolyte history and properties has a strong effect on the anodization current behavior. In a parallel illustration of nanotube length mapping analysis, we also investigate evolution of nanotube morphology in freshly prepared and used electrolytes in relation to the change in real-time current density for titanium anodization in dimethyl sulfoxide/ethanol mixture. It is believed that reactivity of DMSO could be inhibited by the effect of ethanol incorporation that could possibly be a drawback in slowing down those ion movements in the electrolyte, consequently affecting the pore growth and thus the nanotube length.