Study On The Gas Sensing Performance Of Indium-based Oxide Composites With Hierarchical Structure Constructed By Electrospinning

With the advancement of global urbanization,air pollution is becoming more serious.Harmful gases in the atmosphere can have a huge impact on human health and the stability of ecosystems.Therefore,real-time monitoring of air quality to achieve source control has become a common need of society.Semiconductor metal oxide-based chemical sensors have gradually become a research hotspot in many gas detection equipment due to their unique advantages.Among many semiconductor metal oxides,In₂O₃has high electron mobility and good stability,which contributes to its outstanding gas sensing properties and shows good detection potential in many sensitive materials.How to further improve the gas sensing performance of In₂O₃based gas sensors is a concern for domestic and foreign scholars.In recent years,the regulation of material morphology and structure,the addition of a second component,and the assistance of external conditions have been considered effective sensitization pathways for semiconductor metal oxide based chemical sensors.Therefore,this article first synthesized In₂O₃based sensitive materials through electrospinning technology,whose unique one-dimensional linear structure provides a good reaction interface for analyzing gases.Next,a second component doping strategy was adopted to construct indium oxide based composite materials,further improving gas sensing characteristics.The specific research content is as follows:（1）Zn O is used as the second component because of its energy level structure matching with In₂O₃.Several groups of Zn O/In₂O₃composites were prepared by coaxial electrospinning.With the addition of Zn O,the particle size in the composites generally decreases,showing a larger specific surface area,providing more active sites for the adsorption of gas molecules,and then showing enhanced gas sensing characteristics compared with pure In₂O₃.At the working temperature of 120℃,the In1/Zn1 sample shows better gas sensitivity to NO₂.At the same time,it also shows good selectivity to NO₂and fast response recovery characteristics.The strategy of improving the sensing performance by introducing another semiconductor metal oxide can provide new parameters for the construction of advanced NO₂gas sensors.（2）Materials with heterostructure are attractive candidates for constructing NO₂sensors with high gas sensitivity.In this chapter,In₂O₃/Ce F₃composites with heterostructure were synthesized by electrospinning technology and subsequent calcination process.XRD,SEM,TEM and XPS results show that the composite material consists of One-Dimensional（1D）In₂O₃nanotubes and Zero-Dimensional（0D）Ce F₃Quantum Dots（QDs）,in which Ce F₃QDs are uniformly grown on the surface of In₂O₃nano-beams.The heterostructure introduced by Ce F₃QDs not only establishes an electron transport channel between In₂O₃and Ce F₃,but also effectively separates electrons from holes,making more electrons participate in the redox reaction at the gas-solid interface.The gas sensing test shows that at 130℃,the sensor based on In/Ce_0.2shows the best gas sensing characteristic（335）for 10 ppm NO₂,which is 7.97 times that of pure In₂O₃.In addition,it shows good response/recovery characteristics（141 s/30 s）,low detection limit（50 ppb）and high moisture resistance.Finally,the gas sensing mechanism of In₂O₃/Ce F₃composites with good gas sensing performance for NO₂is discussed.