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 degrees C. The nanowire cores are single-crystalline rutile TiO2 with diameters of 15-20 nm and the conical carbon shells are amorphous with gradually decreasing thicknesses from 200-300 nm at the bases to 5 - 10 nm 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. (C) 2008 American Institute of Physics.