Titania nanotube formation in chloride and bromide containing electrolytes

Titania nanotubes and nanofibers were grown by anodization of titanium in fluoride-free electrolytes composed of NaCl and KBr dissolved in either water, ethylene glycol (EG), glycerol, or 50/50 mixtures of water and EG, and water and glycerol. The tubes and fibers grew out of pits in the titanium foil. The 15 nm diameter of the nanotubes was significantly smaller, and the growth rates were much faster than those of tubes developed in fluoride solutions. Nanotubes were nucleated in all electrolytes investigated, but the tubes’ lengths were limited to a few nms in EG and glycerol. Nanofibers produced in the aqueous solutions and nanotubes formed in the 50/50 aqueous mixtures grew to many tens of microns in less than 60 s.