Electrodes for solid electrolyte sensors for the measurement of CO and H2 content in air

Using a test-tube made of yttria-stabilized zirconia (YSZ) as a measuring cell, different simple oxides MexOy (M = Zn, Sn, Cr, In), complex oxides with perovskite structure (La0.8Sr0.2CrO3 and La0.6Sr0.4MnO3) and silver are studied as sensing electrodes (working electrodes) for analyzing non-equilibrium gas systems, containing oxygen and fuel gases, CO or H2. A silver electrode fed with air is used as the reference electrode. The measurements are carried out in the temperature range 450–700 °C and the CO and H2 concentration in air varies from 50 to 100 ppm up to 3.3%. It is stated that the highest responses are demonstrated by the electrodes made of SnO2, Cr2O3 and La0.8Sr0.2CrO3. The results of the investigations are of great practical interest for the development of industrial gas sensors.