Effect of nanostructured WO3 layers in the sensitivity to nitrogen oxide in YSZ-based electrochemical sensors for automotive applications

The sensitivity to nitrogen monoxide (NO) is studied and compared when using several YSZ-based electrochemical gas sensors with identical characteristics but covered by different porous layers over one of their catalytic Pt electrodes. Sensors are exposed to several exhaust gas mixtures containing nitrogen monoxide. The gases are composed by a low concentration of NO dissolved in N2 atmosphere or by a low concentration of NO dissolved in a multi-component mixture similar to exhaust gases from internal combustion engines. The optimum layer thickness and preparation temperture to enhance NO sensitivity are studied. Regarding the composition of the layers, layers made of nanostructured WO3 mixed with porous YSZ seem to maximize the NO sensitivity and decrease crossed sensitivities.