One-step growth and field emission properties of quasialigned TiO2 nanowire/carbon nanocone core-shell nanostructure arrays on Ti substrates

Quasialigned nanoarrays consisting of TiO2 nanowire cores and carbon nanocone shells have been produced directly on titanium foils via a simple one-step thermal reaction under acetone vapor at 850°C. The nanowire cores are single-crystalline rutile TiO2 with diameters of 15–20nm and the conical carbon shells are amorphous with gradually decreasing thicknesses from 200–300nm at the bases to 5–10nm at the tips. Disparity of precipitation and etching of carbon shell give rise to the conical shape. Such TiO2∕C nanocone arrays on a conducting substrate are a new member of the conical nanostructures and promising field electron emitters.