Freestanding TiO2 nanotube arrays with ultrahigh aspect ratio via electrochemical anodization

Self-organized, freestanding titania (TiO2) membrane with ultrahigh aspect ratio of the length/diameter (similar to 1500) was fabricated via electrochemical anodization of highly pure titanium (Ti) foil in fluorine-containing ethylene glycol, followed by a simple and safe detachment of the formed TiO2 membrane from the metallic Ti substrate. The resulting membrane consists of highly ordered, vertically aligned, one-side open TiO2 nanotube arrays. The pore diameter, wall thickness, and length of the nanotube arrays are 90 nm, 15 nm, and 135 mu m, respectively, at a certain anodization condition.