Solid-state amperometric CO2 sensor using a lithium-ion conductor

A solid-state amperometric CO2 sensor was fabricated by combining a Li+-ion conductor (Li2CO3–Li3PO4–Al2O3) with a porous layer and a Li2CO3 auxiliary layer deposited on sensing and counter electrodes, respectively. The Li+-ion pumping current increased linearly with increasing CO2 concentration ranging from 200 to 2000 ppm at 400 °C and the 90% response time was approximately 55 s. This sensor was able to reliably detect a small change in the CO2 concentration.