Silver Growth on Tungsten Oxide Nanowires for Nitrogen Dioxide Sensing at Low Temperature

Gas sensors produced and working at low temperatures are particularly interesting for their compatibility with temperature sensitive substrates such as flexible ones or for their use in specific environments. In this work, we present the chemical synthesis of silver nano-islands grown on ultrathin tungsten oxide nanowires (Ag/WO3 NWs) in order to obtain sensing materials for nitrogen dioxide (NO2) detection at temperatures below 150 °C. We compare the efficiencies of NO2 gas sensing, for WO3 NWs both before and after the silver growth, by drop-casting the nanomaterials from colloidal solutions onto substrates. Interestingly, the working temperature is reduced down to 130 °C even for NO2 concentrations as low as 0.2 ppm, with a clear improvement in sensitivity in the case of the Ag/WO3 NWs. Additionally, continuous UV irradiation reduced greatly the recovery time.