Research Of The Sensor Based On NASICON And Perovskite-type Composite Oxide Electrode For Toxic Gas Detection

The rapid and real-time detection of toxic gases in the surrounding environment is considered as a useful means to achieve gas leakage monitoring in the microenvironment and carry out statistical analysis for the atmospheric environmental disasters.Therefore,developing the solid-state gas sensor is considered as a target with great significance,which can be widely used in atmospheric environment monitoring,food inspection and medical diagnosis.Based on NASICON solid-electrolyte mixed-potential gas sensor,we developed SO₂ gas sensor for atmospheric environment monitoring,triethylamine gas sensor and acetone sensor for volatile organic compounds?VOCs?detection by designing and fabricating new sensing electrode materials.In addition,the above-mentioned sensors were in accordance with mixed-potential theory which were verified by polarization curve.The main contents of this paper are as follows:?1?We developed two kinds of sensors for low-concentration SO₂ detection.As for the sensor attached with La_0.5Sm_0.5FeO₃-SE,the sensing material La_xSm_1-xFeO₃?x:0.2,0.4,0.5,0.6,0.8?was prepared by sol-gel method.It is found that the sensor attached with La_0.5Sm_0.5FeO₃-SE displayed the highest response value at 275°C and the low detection limit of the sensor was 5ppb.In addition,the complex impedance curve of the sensor was measured to investigate the effect of different substitution ratios x on the sensing performance,and sensing mechanism of the sensor comfort to the mixed potential theory which was verified by the polarization curve.As for the sensor utilizing the mixture of V₂O₅,WO₃ and TiO₂,we studied the effects of different mixing ratios on the sensing performance of the sensor.According to the sensing property comparison of the sensor utilizing different sensing materials,we found that the sensor attached with 3%VWT?m?V₂O₅?:m?WO₃?:m?TiO₂?=3:8:89?showed the highest response value and the lowest operating temperature.In addition,we explored reproducibility,selectivity and other gas sensitivity properties.?2?Aiming at triethylamine detection in food inspection and microenvironment testing,we explored the effect of B-site element in the sensing material SmMO₃?M:Cr,Co,Al?on sensing characteristic.The sensor attached with SmCrO₃-SE showed the highest response value among all sensors,and the response value of the sensor towards100ppm trimethylamine is-108.2mV.In order to elevate the sensing performance of the sensor and explore the effect of A-site element on the characteristic,we synthesized MMnO₃?M:Gd,Sm,La?by sol-gel method.By comparing the response values of the three sensors towards 50ppm triethylamine,the sensor with SmMnO₃-SE showed the highest response value,and the polarization curve was measured to analyze the influence of the A site element on the gas sensitivity of the sensor.?3?For the acetone detection,we fabricated the gas sensor attached with Ca_x La_1-xMnO₃-SE.By comparing the influence of different Ca²⁺substitution ratio on the gas sensitivity of the sensor,it was found that the sensor utilizing Ca_0.3La_0.7MnO₃ exhibited the highest response value?-93.2 mV?towards 100ppm acetone.In addition,the sensor also exhibits faster response and recovery rate,selectivity and higher sensitivity.Based on NASICON solid electrolytes,we have designed and developed a perovskite compound sensitive electrode material as a means to produce gas sensors for monitoring the atmosphere,indoor air,industrial production,medical diagnosis and many other aspects.The prepared sensor exhibits excellent performance including high sensitivity,excellent repeatability,good stability,etc.,and has good application prospects in practical applications.