Mixed potential electrochemical NO2 sensor with YSZ ceramic electrolyte for monitoring in online vehicle diagnosis system

For real-time and in-situ NOx monitoring in an online vehicle diagnosis (OBD) system, yttria-stabilized zirconia (YSZ) based high-performance NO2 mixed potential sensor was successfully fabricated with an MMn2O4 (M = Co, Cd and Zn) sensing electrode(SE). Compared to CdMn2O4 and CoMn2O4, the ZnMn2O4 sensing electrode had the smallest interface resistance to 100 ppm NO2, and the sensor based on ZnMn2O4-SE exhibited the highest response. To further improve the sensing performance of the device, the effect of the sintering temperature was studied and the sensor based on ZnMn2O4 sintered at 1000 °C has the highest response of 23 mV to 10 ppm NO2. Moreover, the present NO2 sensor has a wide detection range of 1–1000 ppm, with sensitivities of 18 mV/decade for 1–10 ppm NO2 and 64 mV/decade for 10–1000 ppm NO2. In addition, the device also performs excellent repeatability, terrific selectivity, acceptable O2 resistance and marvelous long-term stability during continuous measurements over 10 days. Overall, based on its excellent sensing performance, the developed sensor has marvelous application prospects for in-situ NOx monitoring in online vehicle diagnosis (OBD) systems.