Doped Semiconductor

Nitrogen doped TiO2 nanotubes (TNT) arrays not only have high surface-to-volume ratios and adsorptive capacity but also have good photocatalytic properties and high photoelectrical conversion efficiency. Also, the nanotubes produced by anodization can permit a careful control over their nanotube diameter, layer thickness, and wall thickness, obtaining structures vertically oriented from the surface. So the TNT arrays have widespread application prospect in dye sensitization solar cells, sensors, hydrogen generation by water photoelectrolysis, photocatalytic degradation of pollutants, and biomedicines.

TiO2 nanotubes could be potentially used for photocatalytic degradation of pollutants in water and gas phases, inactivation of microorganisms, hydrogen production and photo conversion of CO2. However, major disadvantages of using TiO2 nanotubes, which have not been fully overcome, are their relatively large band gap (3-3,2 eV) and high recombination rate of photo generated electron-hole pairs.

Nitrogen-doped TiO2 nanotubes could be prepared via various routes including ion implantation method, chemical bath deposition, ammonia annealing at low and high temperatures, anodization of titanium in the electrolyte containing nitrogen precursor and others. Nitrogen doped Titanium dioxide (TiO2) is one of the most widely studied materials for applications in solar cells, pollutant degradation, photolysis of water, gas sensor, and bio-applications, due to its excellent photocatalytic activity, non-toxicity, high stability, low cost, and biocompatibility.

TiO2 nanomaterials are of great interest because of their large surface area and high light absorption capability. Compared to other nanostructures, Nitrogen doped TiO2 nanotubes arrays (TNAs) are of interest because they can provide a large surface-to-volume ratio and unidirectional electrical channel. Several approaches to incorporate nitrogen into TNAs include one-step direct electrochemical anodization of a TiN alloy, anodization in the nitrogen-containing electrolyte, immersing TNAs in an N-containing solution, and performing a post-annealing treatment.