Synthesis of titanium oxide-Polyaniline nanotube composite and its superior field emission characteristics

Titanium oxide (TiO₂)-Polyaniline (PANI) nanotube composite has been synthesized in two steps. The TiO₂ nanoparticles were synthesized by electrochemical etching of titanium foil and annealing at 500°C in air in the first step; followed by formation of TiO₂-PANI nanotube composite by chemical polymerization using acetic acid as dopant in the second step. The synthesized TiO₂-PANI nanotube composite was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDAX), Uv-visible spectroscopy and Fourier transform infrared spectroscopy (FTIR). The SEM and EDAX results clearly reveal formation of TiO₂-PANI nanotube composite. The TiO₂ nanoparticles (40-50nm) envisaged as adhered to the PANI nanotubes, which are several microns long with diameter of 100-150 nm. The UV-visible and FTIR spectra exhibit the characteristic features corresponding to electrically conducting phase of doped PANI. Field electron emission (FE) studies of the TiO₂-PANI nanotubes composite were performed in planar diode configuration at base pressure of ~ 1×10^-8 mbar. The turn on field required to draw an emission current density of 1 μA/cm² was found to be 0.95 V/μm, and emission current density of 1 mA/cm² has been drawn at an applied field of 2.28 V/μm. The TiO₂-PANI nanotube composite exhibited good emission current stability at preset values of 10 μA over a duration of more than three hours. The present studies indicate the TiO₂-PANI nanotube composite as a promising material for the field emission based applications in vacuum micro-nanoelectronic devices.