NASICON-based potentiometric Cl2 sensor combining NASICON with Cr2O3 sensing electrode

This work focuses on the sensing performance of the sensor to chlorine (Cl2) gas in air based on sodium super ionic conductor (NASICON) and oxide electrode. Among eight single oxides examined, Cr2O3 exhibited the highest sensitivity to Cl2 gas in air at 300 °C. ΔEMF values of the sensing device attached with Cr2O3 changed linearly with the logarithm of Cl2 concentration in the range of 5–50 ppm. The sensitivity of the sensors was testified by using Cr2O3 electrode sintered with different temperature. The sensor using Cr2O3 sintered at 600 °C showed the largest sensitivity to Cl2 at 300 °C. Through burying the reference electrode in middle of the NASICON layer and decreasing the area of the reference electrode, the sensitivity of the sensor to Cl2 can be greatly improved. Finally, a sensing mechanism related to the mixed potential was proposed for the sensor based on NASICON and oxide electrode.