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

A low temperature lithium ion based potentiometric CO
₂
sensor has been developed by adding 10 mol% of SiO
₂
, B
₂
O
₃
, Li
₂
O and Bi
₂
O
₃
composite metal oxide mixture to (Li
₂
-Ba)CO
₃
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 SiO
₂
, Li
₂
O and Bi
₂
O
₃
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 SiO
₂
:B
₂
O
₃
:Li
₂
O:Bi
₂
O
₃
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 CO
₂
concentrations of the test range between 500-5000 ppm. Moreover, increasing Li
₂
O or decreasing B
₂
O
₃
content has shown a deteriorated effect on the performance of the sensor.