Novel Solid Electrolyte CO2 Gas Sensors Based on c-Axis-Oriented Y-Doped La9.66Si5.3B0.7O26.14.

ABSTRACT

Nowadays, monitoring and recording CO2 gas has become more and more important in various areas, leading to increasing demand for developing high-sensitive CO2 sensors. In this study, a novel potentiometric CO2 gas sensor is designed based on a new solid electrolyte of Y-doped La9.66Si5.3B0.7O26.14 (Y-LSBO), coated with the Li2CeO3-Au-Li2CO3 composite as a sensing electrode and Pt as a reference electrode. With the optimized composition of a sensing electrode, the electromotive force (EMF) varies linearly with the logarithm of the CO2 concentration in the range of 400-4000 ppm, exhibiting an excellent Nernstian response to CO2 gas in both dry and humid atmospheres. The fabricated CO2 sensor can be well operated at 400 °C in a dry atmosphere and 450 °C in a humid atmosphere. Based on the results, we have proposed that the good CO2 sensing performance may be associated with Li2CeO3 playing a role of "ionic bridge" between the O2- conductor (Y-LSBO) and the Li+ conductor (Li2CO3). This study not only shows the promising potential of a Y-LSBO solid electrolyte utilized in the field of gas sensors but also enriches the research of solid electrolyte-based potentiometric CO2 gas sensors.