Fabrication of WO3 nanotube sensors and their gas sensing properties

WO3 nanotubes were synthesized using TeO2 nanowire templates. Transmission electron microscopy revealed the nanotubes to have tube diameters, lengths, and wall thicknesses ranging from 100–200 nm, 3–4 μm, and 20–30 nm, respectively. The multiple networked WO3 nanotube sensors showed responses of 144–677% in the NO2 concentration range of 1–5 ppm at 300 °C. These responses were approximately double those observed for the WO3 nanorod sensors over the same NO2 concentration range. A model describing the gas sensing mechanism of WO3 NTs is also proposed.