Sensing Mechanism of Potentiometric Gas Sensors Based on Stabilized Zirconia with Oxide Electrodes

Abstract

The non-Nernstian behavior of zirconia-based electrochemical NOx and CO sensors with various semiconducting oxides as sensing electrodes was extensively studied in the temperature range 450-700°C. Both pellets and tape-cast layers of yttriastabilized zirconia were used for the fabrication of the sensors. It was found that the gas-sensing mechanism of the sensors cannot be explained always by the mixed potential theory. When semiconducting oxides are used as sensing electrodes, the semiconductor sensing mechanism and the adsorption-desorption behavior of the different oxides dominate the sensor response if both metal and oxide are exposed to the same environment.