Carbon dioxide gas sensor with multivalent cation conducting solid electrolytes

A compact carbon dioxide gas sensor is fabricated by using the trivalent (M3+: M=Al, Sc) cation conducting solid electrolyte with an oxide anion conducting stabilized zirconia and lithium carbonate as an auxiliary electrode. The response time which is defined as the time to attain a 90% response is less than several minutes. The sensor output variation with the CO2 concentration shows a clear 1 to 1 relation and obeys the theoretical Nernst relation. The present sensor can detect the CO2 gas concentration accurately even in the atmosphere where nitrogen oxides and water vapor coexist. The response is rapid, continuous, and also reproducible and the performance satisfies the need for practical applications.