Solid state electrochemical gas sensor for the quantitative determination of carbon dioxide

A novel solid state electrochemical sensor is presented that enables the quantitative measurement of CO2 gas in atmospheres of CO2 and O2 in inert gas. The sensor consists of a measuring electrode based on Na2CO3, a series combination of solid ion conductors comprising a ceramic-type component of Na-β/β″-alumina and a salt-type component of Na2SO4, as well as a reference electrode of glass-sealed elemental Na. The sensor yields the thermodynamically expected cell voltage with deviations of less than 1 mV within the temperature range from 300 to 600 °C. At intermediate temperatures, it has a response time on the order of a few minutes, and remains functional and drift-free over several weeks of continuous use. Such results have not before been accomplished since the beginning of this research field more than three decades ago.