Research on Preparation and Performance of a New Solid Electrolyte Based Nitrogen Oxides Sensor

As a major gas pollution source, nitrogen oxide (NO _x , NO + NO ₂ ) poses a serious threat to the natural environment and human health. Therefore, it is imperative to develop high-efficiency detection equipment for in-situ detection of NO _x . The emission sources of NO _x are mainly industrial exhaust gas and automobile exhaust gas. The gas temperature is relatively high and the composition is relatively complicated. The solid electrolyte-based gas sensor can realize high selectivity and high sensitivity detection of NO _x at high temperature. In this study, a Co3O4/Cr2O3/YSZ composite material was used as the sensing electrode (SE) and YSZ was used as the solid electrolyte to prepare the impedance type of NO _x sensor. The sensor was characterized by XRD, SEM and EDX, and the NO _x sensing performance at high temperature was systematically studied. The results show that the Co3O4/Cr2O3/YSZ sensing electrode with particle size of about 200 nm has a high specific surface area due to the loose and porous structure, which is conducive to gas diffusion and mass transfer. The sensor shows a good response-recovery characteristic to NO _x , and the $\text{O}_{{2}}$ concentration has little influence on the sensor. In addition, the sensor shows good reproducibility, stability, and selectivity. In order to further apply the sensor to in-situ detection of NO _x under high temperature, we successfully prepared a novel self heated sensor. The sensor shows good sensitivity characteristics, and the concentration detection range is ${10} \times {10}^{-{6}}$ - ${1500} \times {10}^{-{6}}$ . In addition, the self-heating sensor shows good reproducibility. This research will provide new ideas for in-situ detection of NO _x gas at high temperature.