Fast Growth of Highly Ordered TiO₂ Nanotube Arrays on Si Substrate under High-Field Anodization

Abstract: Highly ordered TiO₂ nanotube arrays (NTAs) on Si substrate possess broad applications due to its high surface-to-volume ratio and novel functionalities, however, there are still some challenges on facile synthesis. Here, we report a simple and cost-effective high-field (90-180 V) anodization method to grow highly ordered TiO₂ NTAs on Si substrate, and investigate the effect of anodization time, voltage, and fluoride content on the formation of TiO₂ NTAs. The current density-time curves, recorded during anodization processes, can be used to determine the optimum anodization time. It is found that the growth rate of TiO₂ NTAs is improved significantly under high field, which is nearly 8 times faster than that under low fields (40-60 V). The length and growth rate of the nanotubes are further increased with the increase of fluoride content in the electrolyte.

Graphical abstract: Highly ordered TiO₂ nanotube arrays (NTAs) on Si substrate have been fabricated by high-field anodization method. A high voltage (90-180 V) leads to a high growth rate of TiO₂ NTAs (35-47 nm s^-1), which is nearly 8 times faster than the growth rate under low fields (40-60 V). Furthermore, the current density-time curves recorded during the anodization provide a facial method to determine the optimal anodization parameters, leading to an easy obtaining of the desired nanotubes.