Zirconia-Based Potentiometric Sensor Using a Pair of Oxide Electrodes for Selective Detection of Carbon Monoxide

By using a pair of oxide electrodes, a stabilized-zirconia-based sensor was developed for selective detection of CO at high tempera-ture. Among the oxide pair examined, the combination of CdO and SnO2 was best suited for the electrode couple, giving quick and selec-tive response to CO in air at 600°C. The 90 % response and the 90 % recovery times of the sensor to 200 ppm CO was as short as ca. 8 and 10 s, respectively, at 600°C. The EMF value was linearly related with the logarithm of CO concentration in the range of 20 to 4000 ppm. Moreover, the cross-sensitivities to other gases, such as H2, NO, NO2, CO2, 02, and H20, were small or insignificant