Preparation Of SnO₂-ZnO Hollow Nanofibers And SnS₂-ZnS Composite Nanoflowers And Research On Gas Sensing Properties

With the development of society,the application of gas sensors becomes wider and wider.Semiconductor gas sensors based on metal oxide sensitive materials exist some defects such as poor selectivity and high operating temperature,which severely restrict their practical applications.How to enhance the sensing performance of gas sensors has become a research hotspot in this industry.In recent years,in addition to modification methods such as rare earth element doping and noble metal modification,it is expected that high-performance sensitive sensors at low temperature or room temperature can be prepared through the construction of heterostructures.Tin dioxide and zinc oxide are two n-type wide band gap semiconductors,which are always hot research materials in the field of sensing.SnS₂ is a group ?-? compound with unique graphene-like structure,high electronegativity and stable chemical properties,which owns certain potential in gas sensing field.Therefore,the metal oxide SnO₂ and metal sulfide SnS₂ are selected as the main research materials in this work,the morphology and dispersion characteristics of the material are optimized through different preparation methods,parameter adjustments,and composites structure,which escalates the adsorption and the conductivity of the material.In this way,the gas-sensing performance is ameliorated.The main work of this paper includes the following:(1)Using the electrospinning method,the uniformly dispersed ZnO-SnO₂ nanofibers were prepared by adjusting the molar ratio of Snand Zn sources.Various characteristics indicated that the sample has good crystallinity and high purity,and the composite material showed the characteristics of n-type semiconductor.At 210?,the sensor based on ZnO-SnO₂ nanotubes has a response of 47.71 to 150 ppm glycol,the response and recovery time are 55s and 13s,respectively.It also exhibited good repeatability and long-term stability.The study found that rough and hollow structure are conducive to gas adsorption and diffusion,and the heterogeneous structure contributes to improve the conductivity of material.(2)We successfully obtained SnS₂-ZnS heterostructured nanoflowers by converting the precursor ZnSn(OH)₆ microspheres.The characterization showed that the samples were flower-like microsphere composed of nanoflakes.The XRD test results proved that the samples own high purity and good crystallinity,no impurities are introduced in the preparation process.The gas sensing performance under different humidity were studied in detail,and all results showed that the sensing performance of SnS₂-ZnS to triethylamine was significantly improved at 180 ? compared with pure SnS₂,and its recovery time was shortened to 2s/8s which increased about 3 times.It also exhibited excellent selectivity and stronger moisture resistance under the same conditions.The excellent gas sensitivities can be attributed to the heterostructure who improves the electrical conductivity of the material,increasing the carrier mobility and the carrier concentration.The highly dispersed flower-like structure of SnS₂-ZnS can provides more adsorption sites for gas,which is another dominant reason.This method also spawn a distinctive ideas for the design of metal sulfide sensitive materials with fast response and recovery time characteristics.