Synthesis of One-Dimensional TiO2 Nanotube Arrays by Potentiostatic Anodisation
TiO2 nanomaterials, in particular nanotubes, are some of the most studied materials, as they are considerably important in technological and biological applications due to their unique electronic properties and biocompatibility. For example, vertically aligned TiO2 nanotubes play a crucial role in photovoltaics as they enhance the charge separation as a result of their excellent photo-catalytic properties in the presence of organic dye molecules, and provide a superior one-dimensional transport route compared to nanoparticle films. There are numerous techniques used to synthesise TiO2 nanotubes, such as chemical vapor deposition (CVD), template based techniques, anodisation, to name but a few. However, due to its non-toxicity environmental friendliness and cost-effectiveness, anodisation is the most common technique to synthesise TiO2 nanotubes. In addition anodisation allows for control over the morphology when tailoring the anodisation parameters such as voltage, concentration, temperature and duration. It is well-documented that the as-synthesised TiO2 nanotubes via anodisation technique are amorphous and require post-treatment at elevated temperature (above 280 degrees C) to induce crystallinity into anatase phase. Further increase in annealing temperature results in crystallisation in either rutile or mixed phase structure.