Preparing large-scale WO3 nanowire-like structure for high sensitivity NH3 gas sensor through a simple route

The large-scale nanowire-like (NW) structure of tungsten oxide is synthesized by the deposition of tungsten metal on the substrate of porous single-wall carbon nanotubes (SWCNTs) film, followed by thermal oxidation process. The morphology and crystallinity of the synthesized materials are analyzed by SEM, TEM, XRD, and Raman spectroscopy. Results showed that tungsten oxide NWs deposited on SWCNTs have a porous structure with an average diameter of about 70 nm and a length of up to micrometers. The NH3 gas-sensing properties of tungsten NWs were measured at different temperatures. A maximum response of 9.7–1500 ppm at 250 °C with rapid response and recovery times of 7 and 8 s are found, respectively. In addition, the gas sensing mechanism of fabricated NWs is also discussed in term of surface resistivity and barrier height model.