Titanium dioxide nanotubes were prepared by refluxing TiO(2) in 10 M NaOH at 200 C for 12 h. The light absorption edge was slightly shifted to a longer wavelength when 0.025 mol % of iron was incorporated to TiO(2) nanotubes. A turn-on field at 12 V/mu m and a maximum current density of 12 mA/cm(2) at 19 V/mu m was observed for the Fe-doped but not for pure TiO(2). The field emission behavior can be correlated with the geometry and electronic states of the nanotubes. (C) 2010 American Institute of Physics.[doi: 10.1063/1.3373607]
