Solid Reference Electrode of SO₂ Sensor Using β-Alumina Solid Electrolyte

The present study was undertaken to find any available solid reference electrode for SO2 sensor employing β-alumina solid electrolyte. We proposed two reference electrodes, Au+Au2Na and (β+β″)-alumina, for such a sensor.Emf measurements of the following cells were performed to investigate the characteristics of the two sodium reference electrodes:Mo, Na(l) / β″-alumina / Au+Au2Na(s), MoPt, Au+Au2Na(s) / β″-alumina / SO2+SO3+O2, PtPt, (β+β″)-alumina in air / β″-alumina / SO2+SO3+O2, PtThe results indicate that constant sodium activities in these reference electrodes are maintained for a long duration of the experiment. It is concluded that the use of Au+Au2Na and(β+β″)-alumina reference electrodes is recommended for the SO2 sensor employing β″-alumina, β-alumina or other sodium ion solid electrolytes.