Effects of titania nanotube distance and arrangement during focused ion beam guided anodization

Abstract

Anodic TiO₂ nanotube arrays possess exciting application potentials in solar cells and photocatalysis. However, self-organized anodization alone can only produce randomly arranged nanotubes. In this study, focused ion beam (FIB) guided anodization is used to create highly ordered TiO₂ nanotube arrays with different intertube distances and tube arrangements. On the one hand, FIB patterning greatly enhances the organization of the nanotubes for the classic hexagonal close packing. On the other hand, fundamentally different nanotube arrangements, such as square, oblique hexagonal, and alternating-sized patterns, are also created. The self-compensating effect enables the development of alternating-sized TiO₂ nanotube hexagonal arrays from graphite lattice FIB guiding patterns. The mechanism of the FIB guided anodization is proposed. This approach presents great opportunities in producing ordered TiO₂ nanotubes and new nanotube arrangements for the desired applications.