Method for Increasing the Porosity of Anodic TiO2 Nanotubes by Anodization in Short Time

Abstract

Various functional modifications of anodic TiO₂ nanotubes (ATNTs) have been widely studied, but the control of porosity of ATNTs is the key to depositing nanofunctional materials into the tubes. It is difficult to obtain ATNTs with a high porosity in a short anodizing process. The morphologies of ATNTs obtained by one-step anodization and two-step anodization were compared in this work. In the process of one-step anodization at 50  V for 30 min, the surface covering layer on the surface of the obtained ATNTs could reduce the porosity of the nanotube arrays (only 4.58%). However, the titanium substrate, with concaves left after the first step anodization in the electrolyte containing polyethylene glycol (PEG600), was once again anodized at 50 V for only 10 min, and the porosity of the formed ATNTs was increased to 21.50%.