Synthesis and Field Emission Properties of Rutile TiO₂ Nanowires Arrays Grown Directly on a Ti Metal Self-Source Substrate

Large-area and uniform quasi-aligned titanium oxide (TiO₂) nanowire arrays have been produced in situ on a titanium (Ti) foil by a simple high-temperature oxidation process with acetone as the oxidant. The products are characterized by X-ray diffraction, electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The TiO₂ nanowires have a rutile single-crystalline structure. The typical diameters range from 20 to 50 nm and lengths are up to a few micrometers. Since the Ti foil serves as both the source of Ti and substrate, direct synthesis and assembly of TiO₂ nanowire arrays on a conductive Ti substrate is accomplished in a single step. Consequently, good intrinsic adhesion and electrical contact are achieved naturally between the nanowires and metal substrate. Such TiO₂ nanowire arrays exhibit good field emission properties with a low turn-on field of 4.1 V/µm boding well for applications in vacuum microelectronics.