Mathematical modelling of YSZ-based potentiometric gas sensors with oxide sensing electrodes: Part I: Model of interactions of measuring gas with sensor

An analysis of transport phenomena through thin-film electrodes for a potentiometric nitrogen oxide (NOx) sensor based on yttria-stabilized zirconia (YSZ) is presented with a focus on the modelling and assessment of non-isothermal and non-isobaric effects (Soret effect) that have not been taken into analysis in previous studies. A mathematical model is formulated for a thin-film planar ZrO2 sensor with Pt and oxide electrodes, taking into account diffusion through the porous electrodes of the humidified exhaust gas containing oxygen and nitrogen dioxide. The competition between molecular and dissociative adsorption as well as heat generation and transfer in the gas sensor has been considered. The adequacy of the presented model is verified by the statistical Fisher criterion. The algorithm of validation of the coefficient of diffusion is also presented.