Highly selective CO sensor using stabilized zirconia and a couple of oxide electrodes

The authors have designed a new solid-state electrochemical device based on stabilized zirconia for selective detection of CO at high temperatures by using two oxide electrodes. Of the oxides tested, the combination of CdO and SnO2 was found to be best suited for the electrode couple, giving a rapid and selective response to CO in air at 600 degrees C. The 90% response time to 100 ppm CO of the sensor obtained was as short as ca. 10 s at 600 degrees C. The EMF value varied logarithmically with the CO concentration in the range of 20-4000 ppm. In addition, the EMF was not significantly affected by the other gases, such as H-2, NO, NO2, CO2, O-2 and H2O. Based on the measurements of anodic and cathodic polarization curves, the authors found that the sensing mechanism of the above sensor involved a mixed potential at both oxide electrodes. (C) 1998 Elsevier Science S.A. All rights reserved.