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 temperature. Among the oxide pair examined, the combination of CdO and SnO2 was best suited for the electrode couple. giving quick and selective response to CO in air at 600 degrees 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 degrees 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 H-2, NO, NO2, CO2, O-2, and H2O, were small or insignificant.