A high temperature potentiometric CO 2 sensor mixed with binary carbonate and glassy ceramic oxide

Abstract

A high temperature (700 °C) lithium ion-based CO 2 sensor was fabricated using Li 2CO 3–BaCO 3 binary carbonate and SiO 2:B 2O 3:P 2O 5 (1:2:1 mol%) amorphous glassy ceramic oxide as sensing electrode. The sensor works efficiently at 700 °C without any degradation of the sensing material. The electro motive force (EMF) of the sensor is very stable and follows perfect Nernstian behavior with the logarithm of CO 2 concentration in the range 500–5000 ppm. It is revealed that Li 2Si 2O 5, Ba 3(PO 4) 2 and quartz were formed at high temperatures (500–700 °C) due to the reaction of Li 2CO 3 and BaCO 3 with glassy ceramic oxide. The time taken by the sensor to reach a change in 90% CO 2 is 10 s. The sensor does not show significant cross-sensitivity to the interfering gases like NO 2 and SO 2 at 500 °C. TG-DTA, XRD, SEM and FT-IR studies were employed to characterize and suggest a probable mechanism. The increase in EMF of the sensor may be due to the easier movement of Lithium ion in to the glass in the sensing electrode.