A Low Temperature Potentiometric CO2 Sensor Combined with SIO2:B2O3:LI2O:BI2O3 Composite Metal Oxide

A low temperature lithium ion based potentiometric CO₂ sensor has been developed by adding 10 mol% of SiO₂, B₂O₃, Li₂O and Bi₂O₃ composite metal oxide mixture to (Li₂-Ba)CO₃ sensing bicarbonate. The sensors attached with different mol% of the above oxides were tested at different operating temperatures. It is observed that the addition of SiO₂, Li₂O and Bi₂O₃ in 1:2:1 ratio to the sensing bicarbonate could effectively decrease the operating temperature to 250-300degC. Further, with the introduction of boron oxide, a glassy sensing electrode phase is obtained resulting improved response and recovery. The sensor attached with 1:2:1:1 mol% of the SiO₂:B₂O₃:Li₂O:Bi₂O₃ composite metal oxide has shown a fair Nernstian correlation and the slope indicate n equal to 2 at 300degC, where n is the number of reaction electrons involved. Remarkably, the sensor is also found stable against humidity (30-70% RH) at all the CO₂ concentrations of the test range between 500-5000 ppm. Moreover, increasing Li₂O or decreasing B₂O₃ content has shown a deteriorated effect on the performance of the sensor.