Characteristics and performance of NASICON-based CO2 sensor using Bi8Nb2O17 plus Pt as solid-reference electrode

The gas sensing properties of NASICON-based CO2 sensor attached with a composite of Bi8Nb2O17 plus small amount of Pt as a solid-reference electrode has been investigated for application of the sensor at high CO2 concentration. Compared with conventional sensor coated with Pt reference electrode, the sensor attached with solid-reference electrode was found to efficiently improve the detection limit due to the presence of solid-reference electrode prevented NASICON reacting with CO2 and water to form carbonate or bicarbonate. A good bonding interface between the solid-reference electrode and NASICON was formed as revealed by the scanning electron spectroscopy (SEM), which provided a powerful guarantee for the thermal stability of the sensor. Furthermore, the as-fabricated sensor also exhibited fast response time, small cross-sensitivity to humidity and little interference from the coexistent oxygen partial pressure at 500 °C. All the present results suggest that using the composite of Bi8Nb2O17 plus Pt as a solid-reference electrode is a promising candidate for NASICON-based CO2 sensor.