HIGHLY SELECTIVE CO SENSOR USING STABILIZED ZIRCONIA AND A COUPLE OF OXIDE ELECTRODES

The authors have designed a new solid-state electrochemical device bas ed on stabilized zirconia for selective detection of CO at high temper atures by using two oxide electrodes. Of the oxides tested, the combin ation of CdO and SnO2 was found to be best suited for the electrode co uple, giving a rapid and selective response to CO in air at 600 degree s 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 logarithmica lly 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 mech anism of the above sensor involved a mixed potential at both oxide ele ctrodes. (C) 1998 Elsevier Science S.A. All rights reserved.