HIGH-TEMPERATURE HYDROGEN SENSOR-BASED ON STABILIZED ZIRCONIA AND A METAL-OXIDE ELECTRODE

A zirconia-based electrochemical device attached with an oxide electro de was developed for the detection of H-2 in air at elevated temperatu re. Among the oxides tested, ZnO was found to be best suited for the s ensing electrode. The device attached with ZnO showed fairly good sens ing characteristics to 50-500 ppm H-2 in air at 450-600 degrees C. The 90% response and 90% recovery times to 200 ppm H-2 at 600 degrees C f or the ZnO-attached device were 5 s and 10 s, respectively. The EMF va lue of the device was almost linear with the logarithm of H-2 concentr ation. It was also observed that the device exhibited excellent select ivity to H-2 in the coexistence of NO, NO2, CH4, CO2 and H2O, as well as a good long-term stability. On the basis of the measurements of ano dic and cathodic polarization curves, the sensing mechanism was confir med to involve a mixed potential at the oxide sensing electrode.