Beta″-alumina solid electrolytes for solid state electrochemical CO2 gas sensors

Abstract The application of surface modified Na-β″-alumina solid ionic conductors for the potentiometric detection of CO 2 partial pressures at ambient and moderately increased temperatures has been investigated. The galvanic cell voltage is decreased compared to the thermodynamically expected value for the formation of Na 2 CO 3 . This indicates kinetically more favorable cell reactions that produce metastable compounds. The redox process involves 4 electrons for each CO 2 and 2 electrons for each O 2 molecule at the applied temperature (150°C). The investigations show that Na-β″-alumina allows to build up potentials which depend on the CO 2 partial pressure.