Potentiometric gas sensors for oxidic gases

Solid electrolyte-based electrochemical devices combined with an auxiliary phase of oxyacid salt have, in this decade, emerged as new attractive sensors to detect oxidic gases of CO2, NO, NO2 and SO2. Various combinations of solid electrolytes and auxiliary phases as well as various new single or multi-component auxiliary phases have been exploited to improve the gas sensing properties and stability of these devices. Some of the potentiometric sensors developed e.g., CO2 sensors using NASICON and Li2CO3-CaCO3, NO2 sensors using NASICON and NaNO2-Li2CO3 and SO2 sensors using MgO-stabilized zirconia and Li2SO4-CaSO4-SiO2, exhibit excellent gas sensing performances in laboratory tests and appear to be promising for monitoring the respective gases in ambient environments and/or combustion exhausts. This paper aims at describing our exploratory works on and the state of the art of these potentiometric gas-sensing devices.