High-temperature stabilized zirconia-based sensors utilizing MNb2O6 (M: Co, Ni and Zn) sensing electrodes for detection of NO2

Mixed-potential type sensors utilizing stabilized-zirconia (YSZ) and MNb2O6 (M: Co, Zn and Ni) sensing electrodes (SEs) were fabricated and examined for NO2 detection at high temperature. For mixed potential type NO2 sensor present fabricated, the device attached with CoNb2O6-SE has been found to give the highest response at 750 °C compared with the other two devices and could detect even 0.1 ppm NO2 with an acceptable response value (5 mV). The present sensor showed fast response and recovery times to 100 ppm NO2 at 750 °C, which are 3 s and 15 s, respectively. ΔV of the sensor attached with CoNb2O6-SE exhibited segmentally linear relationship to the logarithm of NO2 concentration in the ranges of 0.1-2 ppm and 2-300 ppm, which the sensitivities were 10 and 52 mV/decade, respectively. Moreover, the present device also displayed good repeatability, good wet resistance, slight drifts in 30 days high- temperature measured period, and excellent selectivity in the presence of various interfering gases at 750 °C. Additionally, the mixed potential sensing mechanism was explained quantitatively and further demonstrated from the measurement of polarization curve.