A Potentiometric \hbox Sensor Combined With Composite Metal Oxide and DOP Plasticizer Operative at Low Temperature

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 added with different mol% of oxides were tested at different operating temperatures. The sensor with 1:2:1:1 mol% of the SiO 2 :B 2 O 3 :Li 2 O:Bi 2 O 3 composite metal oxide showed a fair Nernstian correlation and obtained n value equal to 2 at 300degC, where n is the number of reaction electrons. A glassy sensing phase resulted that improved response and recovery. The sensor is also found stable against humidity (70% RH) at 300 degC. However, it is further observed that the performance of the sensor deteriorated with increasing Li 2 O or decreasing B 2 O 3 content. The sensor performance could further be improved at lower temperatures with the introduction of dioctyl phthalate (DOP) plasticizer into the sensing electrode.