Nature of Atomic and Molecular Nitrogen Configurations in TiO2-xNx Nanotubes and Tailored Energy-Storage Performance on Selective Doping of Atomic N States

The nature of atomic and molecular nitrogen configurations in TiO 2-xNx nanotubes and tailored energy-storage performance on selective doping of atomic N states was investigated. The highly ordered nitrogen-doped TiO2 nanotubes including mainly atomic N states were prepared by the anodizing process combined with nitrogen plasma treatment. The anodizing process was employed to produce highly ordered TiO2 nanotubes. The obtained nanotubes were annealed at 450°C for 1 h and then the samples were exposed to a nitrogen plasma for 5 minutes. The nitrogen plasma was formed by 500 W of microwave power and a nitrogen gas flow of 100 sccm, and the temperature was continuously increased to 200°C. It was observed that the nitrogen-doped nanotubes do not change the anatase structure of pure TiO2 if nitrogen doping levels are small.