Optimizing Anodization Conditions for the Growth of Titania Nanotubes on Curved Surfaces

Titania nanotubes (TNTs), fabricated by electrochemical anodization due to their outstanding properties, have been widely explored for solar cells, catalysis, electronics, drug delivery, biosensing, and medical implants. Rational design of the anodization conditions is the key to obtaining high quality TNTs that are well aligned and strongly adherent onto the underlying titanium substrate. With the development of many anodization procedures on a substrate with various shapes and sizes, catering to various applications, the mechanical stability of anodic layers is often neglected. Here we consider the factors that lead to unstable and poorly adherent nanotube arrays produced upon anodization of curved titanium surfaces. The role of electrolyte aging, water content, voltage/time of anodization, and the substrate dimensions were investigated for optimization of the fabrication of nanotubes on curved surfaces such as Ti wires. Finally, the most optimal fabrication procedure and anodization parameters are presented that yield high-quality nanotubes, which are stable and well-adherent on the underlying substrate.