SENSING MECHANISM OF POTENTIOMETRIC GAS SENSORS BASED ON STABILIZED ZIRCONIA WITH OXIDE ELECTRODES: IS IT ALWAYS MIXED POTENTIAL?

摘要

The non-Nernstian behavior of zirconia-based electrochemical NO_x 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 yttria-stabilized zirconia (YSZ) 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.