Growth of TiO₂ Nanotube Arrays using Porous Anodic Alumina Templates

Abstract

The aim of this research study is to produce high quality TiO₂ nanotube arrays. It is shown that sol-gel electrophoresis is a suitable one to obtain vast-area TiO₂ nanotube arrays when nanoporous alumina templates are used. To fabricate TiO₂ nanotube arrays, alumina templates were produced via a two-step anodizing by a homemade anodizing cell using high purity phosphoric acid as the electrolyte with aluminum and platinum as electrodes. The semiconductor behavior of these templates can also be employed when producing conducting substrates for the grown TiO₂ nanotubes. Stabilized titanium sol was prepared by modified hydrolysis of the titanium precursor using acetic acid. In order to produce TiO₂ nanotube arrays, the template pores were filled with the precursor sol by applying a DC electric field. Then, the filled template was heat treated to crystallize the desired TiO₂ phase. Scanning electron microscopy of TiO₂ nanotube arrays showed that the nanotubes have been deposited in the channels of the nanoporous alumina template. X-ray diffraction data confirmed phase structure and composition of TiO₂ nanotube arrays after heat treatment. To reach pure anatase phase, the samples were heated at 320°C and 400°C for two hours. To obtain pure rutile phase, the samples were heated at 320°C and 750°C for two hours.