Drift phenomena of electrochemical CO2 sensor with Pt,Na2CO3/Na+-electrolyte//YSZ/Pt structure

The CO2 sensing characteristics of the Pt,Na2CO3/Na+-electrolyte//YSZ/Pt structure were examined under dry conditions. To achieve a good interconnection between YSZ and a dense electrolyte, the Na2O-Al2O3-4SiO2 melt was used as the electrolyte. The electrolyte was stable in syn-air and also in 100% CO2. The sensing characteristics were strongly influenced by the preparation scheme of the auxiliary electrode with Na2CO3. For the sensor with the auxiliary electrode of Na2CO3 formed by the heating of a coated Vaseline mixture with Na2CO3, the tendency to increase the emf was depressed. This observed improvement was attributed to the reduced crystallization and aggregation of Na2CO3 particles due to the coexistence of the oxidized Vaseline in the forming procedure.