文摘
A compact stabilized zirconia-based planar-type solid state electrochemical gas sensor using columbite type MnNb2O6 sensing electrode (SE) was designed and developed, aiming at monitoring low concentration of SO2 at high temperature. Among the different sensing electrode materials calcinated at 800, 1000 and 1200 °C, the device utilizing MnNb2O6-SE sintered at 1000 °C displayed the highest response of −27 mV to 5 ppm SO2 and the low detection limit of 50 ppb at 700 °C. A linear dependence of ΔV for the sensor attached with MnNb2O6-SE sintered at 1000 °C on the logarithm of SO2 concentration in the range of 0.05–5 ppm at an operating temperature of 700 °C was achieved, which the sensitivity was −13 mV/decade. The present sensor showed fast response time of 37 s to 1 ppm SO2 at 700 °C. Furthermore, the present device also displayed good continuous response and recovery, high temperature stability and selectivity toward various interfering gases at 700 °C. Additionally, the sensing mechanism related to mixed potential was proposed and further demonstrated based on the measurement of polarization curve.
