Fabrication of TiO2 rod in tube nanostructure with enhanced photocatalytic activity: investigation of the effect of the states of the precursor on morphology

Here, we report a special rod in tube nanostructured TiO2 prepared by a moderate esterification reaction. The morphology evolution with reaction time was observed by FSEM and FETEM. Comparing to the as-reported sphere in sphere nanostructured TiO2, the formation of a rod in tube nanostructure was attributed to the use of a solid precursor. The nucleation-dissolution-anisotropic grain growth-recrystallization mechanism is responsible for the formation of the rod in tube nanostructure. Moreover, the photocatalytic properties of different morphologies of samples were also compared, indicating that the rod in tube nanostructured TiO2 possessed the best photocatalytic activity. The improvement of photocatalytic activity is mainly attributed to the enhancement of light-harvesting and the separation of electron–hole pairs. Finally, the present work also provided a template-free method to synthesize hierarchical porous TiO2 nanotube through prolonging reaction duration.