Gas Sensing Properties of WO₃ Nanowires Decorated with Iridium Oxide Nanoparticles

Abstract

Tungsten trioxide (WO3) nanowires decorated with iridium oxide nanoparticles (WO3-IrO2) have been studied as candidate towards low NO2 concentrations gas detection. Furthermore, reducing gases such ammonia vapors and hydrogen have been also studied. WO3 nanowires were grown following an aerosol assisted chemical vapor deposition (AACVD) methodology; and decorated in two steps. As first step, nanowires were grown and subsequently annealed at 500 °C for two hours in order to remove impurities and enhance the oxidation ratio. In a second step, employing an iridium oxide nanoparticles suspension they were decorated through AACVD. Iridium oxide nanoparticles were synthetized from an inorganic precursor through an acidic hydrolysis synthesis route. The sensors were also characterized through environmental scanning electron microscopy (ESEM) and X-ray photoelectron spectroscopy (XPS). All iridium oxide based sensors shows a higher response towards all the gases tested in comparison towards pristine sensors, despite showing the best performance towards NO2.

Keywords

• nanowires
• tungsten trioxide
• iridium oxide
• gas sensing
• NO2