Double-cell carbon dioxide sensor based on LiK molten carbonate with electrochemically-supplied CO2–O2 reference

A carbon dioxide sensor using molten carbonate electrolyte with double-cell structure was examined; one cell was employed for electrochemical pumping of CO2 and O2 from ambient atmosphere and the other was used for sensing of the ambient CO2 with the pumped CO2–O2 mixture as a reference gas. The sensor was operated at 600°C for the sensing of CO2-containing air. By sending appropriate current, the pumping cell could provide CO2 and O2 at 2/3 and 1/3 of the atmospheric pressure, respectively. The sensing cell showed EMF with respect to the CO2 and O2 partial pressures against the pumped CO2–O2 reference gas. The sensor could determine the partial pressure of CO2 in the examined range of 26 to 1×104 Pa (260–100,000 ppm).