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

• SnO2, Cr2O3 and La0.8Sr0.2CrO3 are proposed for H2 and CO measurement.
• Sensors operating at relatively low temperature interval (500–650 °C).
• Simultaneous measurement of several electrodes under the same conditions.
• Formulation of a new concept of sensor with un-separated gas spaces.
• Tube sensor with extra silver electrode measuring O2 and exposed to the analyzed gas.

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.

An electrochemical sensor for simultaneous analysis of oxygen and combustible gas content in the gas mixtures air –H2 or air –CO is suggested. 1 – solid electrolyte test tube, 2 – working silver electrolyte, 3 – working electrode based on SnO2, 4 – reference silver electrolyte.Figure optionsDownload as PowerPoint slide