Influence of ceramic oxide materials on lithium based potentiometric CO2 sensors

In these potentiometric sensors, a mixed binary carbonate sensing material consisting of 90 mol% Li2CO3 and 10 mol% BaCO3 was modified by adding ceramic oxide materials such as SiO2, B2O3, La2O3, Bi2O3, CeO2 and In2O3 in different mol% concentrations. Various sensors mixed with these external oxides have shown good performance at operating temperatures below 300 °C. Scanning electron microscopy reveals that a glassy sensing phase is formed in the sensing bi-carbonate by the addition of ceramic oxides and sintered at 600 °C for 1 h. The sensor mixed with SiO2:B2O3:Bi2O3 in 1:2:1 mol% showed an excellent response and recovery characteristics and followed a fair Nernstian behavior with a ΔEMF/dec value of −48.18 at as low as 150 °C. The decrease in operating temperature is attributed to the enhanced lithium ion migration through the glassy sensing phase of the sensing electrode.