Temperature dependence of NO2 sensitivity of YSZ-based mixed potential type sensor attached with NiO sensing electrode

摘要

A mixed potential type yttria-stabilized zirconia-based sensor using NiO sensing electrode and Pt reference electrode was fabricated, and its NO2 sensing characteristics were examined at various operating temperatures in the range of 700-950 °C. It was observed that the sensitivity to NO2 strongly depends on the operating temperature of the sensor; the sensitivity decreases with increasing operating temperature, while the response/recovery rates increase. To rationalize this temperature dependence of NO2 response, polarization curves and complex impedances of the sensor were measured in the base gas and in the sample gas (400 ppm NO2+base gas) at various operating temperatures. It turned out that the operating temperature had a strong influence on the rate of anodic reaction of oxygen; the increased rate of anodic reaction leads to lower NO2 sensitivity and quicker response/recovery at higher operating temperature.