Tungsten trioxide nanowires decorated with iridium oxide nanoparticles as gas sensing material

Tungsten trioxide nanowires were grown employing aerosol assisted chemical vapor deposition (AACVD) and subsequently decorated with different loading levels of iridium oxide nanoparticles. AACVD has been already demonstrated to be a useful tool to load different ranges of nanoparticles on top of an already grown layer. This procedure enables growing the gas sensitive nanomaterials directly onto application substrates for the development of chemo-resistive gas sensors. The morphology and composition of the different materials were characterized via different techniques. It was found that iridium oxide loading resulted in remarkable changes in the morphology and defects of tungsten oxide nanowires. The gas sensing properties of such layers were studied towards ethanol or ammonia vapors, hydrogen, hydrogen sulfide, and nitrogen dioxide. The optimization of the operating temperature and the level of iridium oxide loading results in an improvement in the responsiveness and selectivity towards the species tested. In particular, a dramatically high increase in the response towards nitrogen dioxide is achieved. The mechanisms of gas sensing are discussed in detail. (C) 2019 Elsevier B.V. All rights reserved.