Electrochemical NO2 Sensor Using a NiFe1.9Al0.1O4 Oxide Spinel Electrode

A novel solid-state electrochemical sensor using (Sc2O3)0.08(ZrO2)0.92 (ScSZ) electrolyte solid and a NiFe1.9Al0.1O4 oxide spinel electrode was tested for the detection of NO2 at temperatures greater than 700 degrees C for automobile applications. The sensor was found to respond rapidly, reproducibly, and selectively to NO2 at 703 and 740 degrees C. The response time of the sensor was approximately 8 s, and the recovery time was 10 s at both 703 and 741 degrees C. The response of the sensor was highly reproducible to the change in concentration of NO2 and also showed negligible cross-sensitivity to potentially interfering gases such as O2, CO, and CH4 in the gas stream.