Several different synthetic methods have been developed to fabricate
tungsten oxide (WO(3)) nanostructures, but most of them require exotic
reagents or are unsuitable for mass production. In this paper, we present a systematic investigation demonstrating that
arc discharge is a fast and inexpensive synthesis method which can be used to produce high quality
tungsten oxide nanostructures for NO(2) gas sensing measurements. The as-synthesized WO(3) nanostructures are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), finger-print Raman spectroscopy and
proton induced x-ray emission (PIXE). The analysis shows that spheroidal-shaped monoclinic WO(3) crystal nanostructures were produced with an average diameter of 30 nm (range 10-100 nm) at an
arc discharge current of 110 A and 300 Torr
oxygen partial pressure. It is found that the morphology is controlled by the
arc discharge parameters of current and
oxygen partial pressure, e.g. a high
arc discharge current combined with a low
oxygen partial pressure results in small WO(3) nanostructures with improved conductivity. Sensors produced from the WO(3) nanostructures show a strong response to NO(2) gas at 325 °C. The ability to tune the morphology of the WO(3) nanostructures makes this method ideal for the fabrication of gas
sensing materials.