Effects of Electrode Microstructures on the Sensitivity and Response Time of Mixed-Potential NO2 Sensor Based on La0.6Sr0.4CoO3 Sensing Electrode

Metal oxide La
_0.6
Sr
_0.4
CoO
₃
was chosen as a sensing electrode for the mixed potentiometric NO
₂
sensor based on yttria stabilization zirconia (YSZ). The La
_0.6
Sr
_0.4
CoO
₃
sensing electrodes were sintered at 800°C, 900°C, 1000°C, and 1100°C separately to obtain different microstructures. The relationship between the La
_0.6
Sr
_0.4
CoO
₃
sensing electrode microstructures and the NO
₂
sensing performances was described. The La
_0.6
Sr
_0.4
CoO
₃
sensing electrode sintered at 1000°C had the biggest porosity of 29.8%, while the sensor based on it exhibited the maximum response of 141.1 mV at 500 ppm NO
₂
and the first-rank sensitivity of 80.3 mV/decade at 400°C. The sensor also showed high stability and selectivity. Different microstructures of the sensing electrode corresponded to different triple-phase boundaries, which was the main place for NO
₂
detection, so the performances were affected. Moreover, the result of the electrochemical impedance spectrum also proved the triple-phase boundary played an important role in NO
₂
detection.