Solid state electrolyte type gas sensor using stabilized zirconia and MTiO3 (M: Zn, Co and Ni)-SE for detection of low concentration of SO2

This paper deals with solid state electrolyte type gas sensors based on mixed potential mechanism using yttria-stabilized zirconia (YSZ) as solid electrolyte and MTiO3 (M: Zn, Co and Ni) as sensing electrodes (SEs) for monitoring very low concentrations of SO2 in atmospheric environments. Among all the devices attached with different SEs, ZnTiO3-SE brought about the highest response value of -22.5 mV to 1 ppm SO2 at 600 degrees C and even down to 100 ppb SO2 with the response value of -2.5 mV. Meanwhile, the measured Delta V of the sensor was found to vary linearly as a function of the logarithm of SO2 concentration in the range of 100 ppb(-2) ppm at 600 degrees C and the sensitivity (slop) was -23 mV/decade. In addition, the sensor coupled with ZnTiO3-SE gave negligible responses to other interfering gases such as C2H2, CH4, CO, NO2, NO, NH3. Furthermore, the present sensor possessed good repeatability, slightly affected by the change of oxygen concentration and relatively stability during 20 days of continuous high-temperature operation. Moreover, the polarization-curve measurements demonstrated that the good agreement between the observed sensitivity and the estimated value, confirming that the sensing mechanism was based on mixed-potential model.