Research On Solid Electrolyte Gas Sensor Based On Zirconia

Gas sensors are devices that convert gas concentrations into electrical signals.They are now widely used in the fields of human industry,military,energy,and medical.This article focus on zirconia?YSZ?based solid electrolyte gas sensors.Starting from the preparation of sensitive electrodes and the structure of the solid electrolyte layer,porous zirconia layers prepared by doping stabilized zirconia with different graphite concentrations are used as solid electrolytes,and La Fe O₃is used as a sensitive electrolyte.High-performance solid-state electrolyte gas sensors were fabricated,and the gas sensitivity characteristics of the prepared gas sensor to NO₂and ethanol were systematically studied.By fitting the gas response curve,it is verified that the above-mentioned sensor's sensitive mechanism is a hybrid potential mechanism;by preparing a porous zirconia layer,the area of the three-phase reaction interface is increased,and the performance of the sensor is improved.The main contents of the thesis are as following:1.LaFeO₃ sensitive electrode material was prepared by a sol-gel method,and solid electrolyte gas sensors based on La Fe O₃sensitive electrode and YSZ was fabricated by screen printing technology.La Fe O₃ministerial with different gas sensitivities were obtained by changing the sintering temperature of La Fe O₃?500,700,and 900??.Finally,the performance of the prepared gas sensor was tested to study its influence on the sensor's sensitive characteristics.The results show that the gas sensor prepared with La Fe O₃calcined at 700?has the highest response to 100 ppm NO₂gas under the working condition of 400?,reaching 16.3 m V.This is because La Fe O₃has good catalytic performance for NO₂,and benefits from the good microstructure formed by the sensitive electrode and the stable zirconia substrate.2.In order to improve the performance of the prepared gas sensor,starting from building an efficient three-phase reaction interface,and using screen printing technology to fabricate high-performance porous zirconia-based gas sensors.Porous stabilized zirconia layers with different roughness were prepared by doping graphite with different concentrations?0,3,10,and 15 wt%?into stable zirconia.Finally,through the performance test of the prepared gas sensor,it was found that the obtained gas sensors had the best performance when the graphite doping concentration was 3wt%,and the response to 100 ppm NO₂gas was 81 m V at a working temperature of250°C.The response to 400 ppm ethanol at 350°C is 139.8 m V.The reason for the improved performance of the fabricated gas sensor is that graphite doping makes the stabilized zirconia substrate rough,resulting in an increase in the contact area between the sensitive electrode and the solid electrolyte substrate,effectively increasing the area of the three-phase reaction interface,and promoting the electrochemical reaction.However,as the doping concentration of graphite further increases,the adhesion of the porous zirconia layer becomes worse,resulting in a poorer degree of bonding between the porous layer and the electrode,the interface resistance of the two will increase,and the performance of the sensor will eventually decrease.In addition,the fabricated sensors also exhibit good stability,repeatability,and selectivity.