Field emission of vertically aligned V₂O₅ nanowires on an ITO surface prepared with gaseous transport

Growing V₂O₅ nanowires (NWs) on a conducting glass substrate combines gaseous transport and pyrolytic deposition of vanadium polyoxometalate anions, and yields vertically aligned vanadium-oxide nanowires. Scanning electron and transmission electron microscopy, selected-area electron diffraction, Raman spectra and powder X-ray analyses indicate that V₂O₅ nanowires as synthesized were single-crystalline and grew anisotropically among direction [010]. NH₂OH·HCl served not only as a reducing agent to produce vanadium polyoxometalate clusters but also as a source of NH₃ gas to facilitate the vapor pyrolysis and deposition. The optical properties of V₂O₅ nanowires exhibit a character dependent on structure. Field emission (FE) measurements show a small turn-on field voltage ~8.3 V/μm, maximum current density 1.8 mA/cm², and a linear Fowler-Nordheim behavior.