Synthesis Of Tin Oxide/Zinc Oxide-based Composites And Their Gas Sensing Performance At Roomtemperature

Nitrogen dioxide gas?NO₂?is a common air pollutant produced in the combustion process of automobile engines,industrial production and generators.Due to the toxicity of nitrogen dioxide gas,exposure to nitrogen dioxide gas can have serious effects on human health,including olfactory paralysis and respiratory diseases.Therefore,it is necessary to develop a stable gas sensor with high sensitivity and selectivety that can detect low concentration of nitrogen dioxide gas at room temperature.Semiconductor metal oxides,such as tin dioxide,zinc oxide,titanium dioxide,nickel oxide,etc.,are the most studied gas sensing materials due to their excellent gas responsiveness and selectivity.In addition,nano-structures with high surface area and full electron loss are conducive to improving the sensing performance of sensing materials.In particular,one-dimensional nano-structures with such advantages as nanofibers,nanorods and nanotubes are widely used to improve the gas sensing performance.However,single gas-sensitive materials generally have inherent defects such as small response value at room temperature,poor repeatability and limited detection limit.The research shows that the composite gas sensing materials made from a variety of nanomaterials can own the excellent characteristics of a variety of materials at the same time and can show better sensing performance than the single gas sensing materials.Therefore,based on electrostatic spinning technology,a new one-dimensional multi-porous tin dioxide@zinc oxide?SnO₂@ZnO?nano-fiber was designed and prepared in this work.In addition,the gas sensing performance of the composite porous hollow nano-fiber of SnO₂@ZnO at room temperature was further investigated.Finally,the response sensing mechanism of the gas sensor based on the composite porous hollow nano-fiber of SnO₂@ZnO to nitrogen dioxide?NO₂?gas was discussed in detail.In the last part of this paper,a novel flexible wearable electrode was designed and prepared innovatively by using screen printing technology.After 10 000 cycles of 45 degree bending,the resistance remained almost unchanged,and a novel flexible wearable gas sensor was integrated with the prepared SnO₂@ZnO composite porous hollow nano-fiber sample.The details of expriments are as follows:ZnO doped porous hollow SnO₂ nanofibers were successfully prepared by environmentally friendly electrostatic spinning method and one-step molding calcine method.Finally,through the collection and comparative analysis of its gas sensitive performance data,the sensing mechanism of porous hollow SnO₂@ZnO composite nano-fiber was discussed in detail,and the gas sensing mechanism of its detection of nitrogen dioxide gas was further described.The results show that,compared with pure SnO₂ nanometer fiber based on SnO₂@ZnO composite nanofibers gas sensor to 0.5ppm NO₂ gas at room temperature with high sensitivity and selectivity,the response value is as high as 336%,which is contrbutited to the porous hollow SnO₂@ZnO composite nano fiber has high specific surface area?38.68 m²/g?and the effect of the heterojunction.In addition,silver paste electrodes were printed on paper and polyethylene terephthalate?PET?by screen printing technology,and a novel flexible wearable gas sensor was integrated with SnO₂@ZnO porous hollow composite nano-fiber,providing a feasible solution for the development of flexible gas sensor.