High-performance solid electrolyte CO/sub 2/ sensor fitted with binary carbonate electrode

A simple potentiometric CO/sub 2/ sensor based on an Na/sup +/-conducting solid electrolyte (NASICON) was found to be greatly improved in response time and water-vapor resistance by using a binary carbonate electrode of BaCO/sub 3/-Na/sub 2/CO/sub 3/. For a wide range of CO/sub 2/ concentration from 4 to 400000 ppm, the electromotive force examined at 823 K followed a Nernst's equation excellently, with a 90% response time of as short as 8 s or less. Water vapor hardly affected the sensor characteristics, in contrast to the case of a pure Na/sub 2/CO/sub 3/ electrode. The structure and CO/sub 2/ sensing mechanism of the binary carbonate electrode are briefly discussed.< >