A solid electrolyte potentiometric CO2 gas sensor composed of lithium phosphate as both the reference and the solid electrolyte materials

A solid electrolyte potentiometric CO2 gas sensor has been considered as a candidate for miniaturization into a micro-sensor form. However, the solid electrolyte potentiometric CO2 gas sensor is composed of three components: a reference, a sensing material, and a solid electrolyte. This study reports the fabrication of a solid electrolyte potentiometric CO2 gas sensor with a native reference material from the solid electrolyte (Li3PO4), which means one component of the sensor can be omitted and the fabrication process can be simplified compared to the process for a conventional solid electrolyte potentiometric CO2 gas sensor. The sensor containing Li3PO4, which acted as the reference material as well as the sensing material, showed a comparable response (75 mV/dec at 500 °C) to CO2 gas when we compared the sensor with a conventional solid electrolyte CO2 gas sensor (73 mV/dec at 500 °C) with a coplanar configuration containing Li2TiO3 as the reference material and Li3PO4 as the solid electrolyte.