Influence of Humidity on the CO Sensitivity of a New Gas Sensor Based on SnO2 Nanoparticles Surface-Doped with Palladium and Platinum

International audienceIn this paper, we show the influence of two doping agents Palladium and Platinum on the sensitivity for CO sensing of the nanoparticular SnO2 sensors at an operating temperature of 450°C. It is well known that the evolution of the conductance of the sensitive layer is largely modified by doping. A study carried out to measure the influence of humidity demonstrates that if un-doped sensors show a variation of same sign but less important than in dry air, doped sensors display a very different behavior. Indeed, we obtain a point of null sensitivity between 0 and 10%RH (RH = relative humidity) and a strong inverse sensitivity above 15% RH. These results demonstrate the presence of unexpectedly different chemical operating modes for CO sensing according to the rate of humidity