Preparation And Gas Sensitive Properties Of Polymetallic Oxides

The national"Thirteenth Five-Year Plan"strategic emerging industries development plan and"Made in China 2025"are clearly proposed to focus on the development and industrialization of new electronic components such as environmental monitoring gas sensors.The rapid development of the Internet of Things has greatly promoted the widespread use of sensors and sensing technology,and the"Thirteenth Five-Year Plan"issued by the Ministry of Industry and Information Technology also mentions the development of micro and intelligent sensors in the key projects.As one of the core of gas detection system,gas sensor is the focus of gas detection research.It is very important in the fields of national defense technology,industrial safety,medical health,intelligent agriculture,fire and air quality monitoring,especially in the detection of harmful gases.With the wide application of gas sensors in Io T technologies such as smart homes,wearable devices and mobile terminals,the development of practical high-performance gas sensors that are room-temperature,small and easy to integrate has become a focus of attention for researchers.The design and innovation of sensitive materials are the basis for the development of high performance gas sensors,and multi-metal oxides have the advantages of multiple valence cations,adjustable morphology and unique crystal structure.The microscopic morphology of the samples,their component element types and their valence states were investigated through a series of scientific characterizations,and finally,the gas-sensitive mechanism of the sensitive materials was discussed.The specific works are as follows:1.A series of characterization techniques such as XRD,SEM,TEM and XPS show that the prepared samples are SmFeO₃with chalcogenide structure;the surface of the nanoparticles is rough and its roughness is very favorable for the improvement of gas sensitivity.The nanoparticles have excellent sensitivity to ethylene glycol gas,with a response of 117 to 100 ppm of ethylene glycol at an operating temperature of 180℃ and good selectivity.This indicates that the resistive gas sensor based on SmFeO₃ nanomicrospheres is a promising sensor for ethylene glycol.2.HoFeO₃ nanofibers with uniform thickness were obtained by electrostatic spinning as well as high-temperature calcination.A series of characterization methods such as XRD,SEM,TEM,and XPS were used to characterize the microscopic morphology,component element types,and their valence states of the synthesized samples.The characterization data showed that HoFeO₃nanofibers with chalcogenide structure were synthesized.The resistive gas sensors were prepared using the synthesized samples as sensing materials,and their gas-sensitive performance was tested on a gas-sensitive device.The test data showed that the gas sensor based on HoFeO₃ nanofibers has excellent response to ethanolamine gas（7.51）,ultra-low operating temperature（160℃）,and excellent selectivity and fast adsorption/desorption（39s/32s）.It is further shown that the HoFeO3 nanofiber-based resistive gas sensor can be used as an ethanolamine sensor.3.ZnO/ZnCo₂O₄ composites were prepared by a simple one-step hydrothermal method.The gas-sensitive performance of the samples was investigated,and it was found that the gas-sensitive performance of ZnO/ZnCo₂O₄ sensor was significantly improved by modifying ZnCo₂O₄ with ZnO The ZnO/ZnCo₂O₄ sensor has an ultra-low operating temperature（160℃）,good selectivity,repeatability,long-term stability and high responsiveness to ethylene glycol gas（15.63）.Its excellent gas-sensitive performance is due to the formation of p-n heterojunction and its unique microstructure.Therefore,ZnO/ZnCo₂O₄ is a promising gas-sensitive material for ethylene glycol and provides a feasible viewpoint for the preparation of future ethylene glycol sensors.