Solid electrolyte carbon dioxide sensor based on the Na/sub 2/CO/sub 3///NASICON//YSZ structure

To test the stability of the electromotive force (EMF) of the solid electrolyte CO/sub 2/ sensor with Na/sub 2/CO/sub 3///NASICON structure, the potential variations at the cathode (the NASICON/gas interface) and anode (the gas/Na/sub 2/CO/sub 3/ interface) of the cell were separately measured by setting a reference electrode. In air, the EMF of the sensor showed a significant deviation, which was caused by the instability of the cathode electrode. Electrode probe micro analysis (EPMA) detected the formation of Na/sub 2/SO/sub 4/ at the cathode. A novel sensor with a structure in which the NASICON was covered with yttria-stabilized zirconia (YSZ) at the cathode was proposed to prevent the formation of Na/sub 2/SO/sub 4/. This sensor exhibited excellent long-term stability and works well, according to the Nernst equation, in air.<>