Theoretical and experimental studies on the anodic oxidation process for synthesis of self-ordering TiO2 nanotubes: Effect of TiO2 nanotube lengths on photocatalytic activity

Abstract

In this study, TiO2 nanotubes were synthesized via anodic electrochemical oxidation method and the effects of different parameters such as applied voltage, anodization time, electrolyte solution temperature and pH on the outer diameter and length of TiO2 nanotubes in a NH4F/C2H6O2/H2O electrolyte system were investigated. Based on the experiments, length and outer diameter of the synthesized nanotubes were in the range of approximately 9–71μm and 81–171nm respectively which were found by scanning electron microscopy (SEM) analysis technique. Also a generalized theoretical model was developed to predict the morphology (length and outer diameter) of TiO2 nanotubes prepared by anodization method. The collected experimental data based on classic design was used to obtain adjustable parameters in the presented model.Photocatalytic activity of different lengths TiO2 nanotubes were evaluated in terms of the degradation of formic acid in aqueous solution under ultraviolet (UV) light irradiation. Results showed that the optimal tube length would be an important factor to achieve the good photocatalytic performance of TiO2 nanotube arrays. The highest photocatalytic performance was found for the synthesized TiO2 nanotubes with 46μm length.