Anodic formation of anatase TiO2 nanotubes with rod-formed walls for photocatalysis and field emitters

Anatase TiO2 nanotube arrays with rod-formed walls have been fabricated using a one-step anodic oxidation method for the first time. XRD, Raman spectroscopy, SEM, and HRTEM analysis were used for the structural characterization of the synthesized nanostructures. Their photocatalytic and field emission (FE) properties were also systematically investigated, and the experimental results indicated that the crystallization of the starting polycrystalline nanostructures turned into a better anatase phase after the annealed process. The photocatalytic properties showed that the nanostructures with optimized crystallization demonstrated faster degradation rate than the as-prepared polycrystalline counterparts, which would be caused by the improved crystallinity. Furthermore, the dependence of the FE properties on the distances between the anodes and the samples was investigated and the results revealed that the annealed samples have higher field enhancement factor beta compared to the as-prepared nanostructures. The formation mechanism of this novel rod-formed TiO2 nanotubes is also briefly discussed.