Electropolishing for the formation of anodic nanotubular TiO2 with uniform length and density

Electropolishing of Ti was carried out in alcohol-based electrolyte and subsequently the polished Ti was anodized in ethylene glycol containing 0.25 wt% NH4F. Anodization of polished and non-polished Ti, respectively, showed no big difference in the degree of local arrangement of the nanotubes, whereas the surface roughness on a large area was dramatically improved in the anodized polished Ti. Anodization of polished Ti leads to the formation of nanotubular TiO2 structures with more uniform length and relatively time-independent density of nanotubes compared to that prepared with anodization of non-polished Ti, meaning that electropolishing is indispensable for the formation of uniform nanotubular TiO2 structures.