A carbon dioxide gas sensor based on solid electrolyte for air quality control

Abstract

A practical CO 2 gas sensor for air quality control is developed by using a combination of a Na 3Zr 2Si 2PO 12 (NASICON) as a solid electrolyte and Li 2CO 3 as a carbonate phase. The sensor's electromotive force (emf) shows a linear relationship with the logarithm of CO 2 concentration. Zeolite is chosen as a filter material in order to minimize the effect of interfering gases on the sensor's emf and shows very little sensor response deterioration to CO 2. Under continuous energizing, both the emf and a change in the emf (defined as Δemf) are stable over a period of 2 years. However, after the sensor is exposed to a high humidity atmosphere in an unpowered state, the emf decreases, but Δemf stays constant. A new data selection method for renewing the standard of the emf is investigated in order to monitor CO 2 concentration using Δemf. The output of the CO 2 monitor corresponds to a conventional non-dispersive infrared (NDIR) analyzer.