Solid-State Sensor for Sulfur Oxides Based on Stabilized Zirconia and Metal Sulphate

Abstract
Electrochemical cells using MgO-stabilized zirconia tube coated with metal sulphates were found to exhibit fairly good sensing properties to 20–200 ppm SO2 in air at 650–800 °C. With various sulphates such as Li2SO4 and Na2SO4, EMF responses to SO2 followed Nernst’s equations for a 2-electron reduction of SO2. With Li2SO4-CaSO4 (6:4 in molar ratio), 90% response- and 90% recovery-times were 12 s and 2.5 min, respectively, for 130 ppm SO2 at 800 °C.