Highly Sensitive NO2 Sensor Based on Stabilized-zirconia Tube and Nitrite-based Auxiliary Sensing-electrode

概要

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A new type of sensor was fabricated by using a stabilized zirconia (YSZ) tube as well as a potassium nitrite (KNO2)-based auxiliary sensing-electrode (SE), and its sensing performances were examined for detecting low concentration of NO2 at 450°C. The difference in potential (emf) between the nitrite-based SE and the Pt/air reference electrode (RE) was measured as a sensor signal. The device was found to detect NO2 rather sensitively down to 20 ppb, although the response time needed to be improved. The NO2 sensitivity of the sensor was hardly varied even if the concentration of CO2 in the sample gas was changed from 400 ppm to 1000 ppm, and the sensitivity varied logarithmically with the NO2 concentration in the range of 20–400 ppb. A new technique proposed here for measuring sensor response could shorten the response time of the present sensor.