Study On Gas Sensing Properties Based On Electrospinning Semiconductor Oxide Nanofibers

The unique physical properties and potential applications of nanomaterials have stimulated the researchers'enthusiasm and rapid development in the fields of spectrum,batteries,biology and sensor.The one-dimensional semiconductor oxide nanomaterials are favored by many researchers because of their unique electrical properties and surface structure.In recent years,electrospinning has been a simple and easy way for the preparetion of one-dimensional semiconductor oxide nanomaterials.It can flexibly control the morphology,structure and composition of one-dimensional nanomaterials,but not confined to it.And it can also be extended to the macroscopic structure,therefore,which has been applied to many important aspects.Among them,the gas sensor is the most widely-used and the most important realms.Although the research on gas sensing of one-dimensional nanomaterials has made some progress,there are still many deficiencies in practical application.Therefore,this paper studied the physical properties and surface structure of one-dimensional semiconductor oxide nanomaterials,designed the high gas sensitive performance semiconductor oxide nanostructures,explores the gas sensor applications in air pollution and the early disease screening,and successfully applied to the actual pollution gas detection and clinical trials.The main results are:[1]Using polystyrene?PS?nanowires as a template with electrospinning,soak in butyl titanate and annealing,got the TiO₂ nanotubes diameter in 250-900 nm,wall thickness in 25-100 nm,and this methord can be extended to other semiconductor oxide nanotubes.Use ZIF-8 metal organic framework structure can disperse Pt nanoparticles,Pt nanoparticle size can be controlled at about 3 nm,and ZIF-8 can be formed ZnO after the process of annealing and protect the Pt nanoparticle.The as-prepared materials carried out morphology and structural characterization,and the results showed that TiO₂ was the crystalline phase of anatase and had a lot of oxygen vacancies on the surface.We studied the gas sensor performance of Pt@ZnO-TiO₂ nanotube for toluene,it showed that the sensitivity has been greatly improved,and the detection limit can reach 23 ppb,it far less than the safety standards in the World Health Organization?67 ppb?.[2]The preparation of the WO₃ nanotubes using the methods in[1],joined the ethyl silicate in order to form SiO₂ after annealing on this basis.It can be removed via the process of hydrofluoric acid etching effect,and form porous WO₃ nanotubes.By adjusting the amount of ethyl silicate to regulate the specific surface area and porosity,the surface area and porosity has more than twice in this case.Based on the limitation of gas-sensing mechanism,APTES modified on the porous WO₃nanotubes to improved the NO₂ gas sensitivity with the case of organic and inorganic hybridization.In the case of P-WO₃ NTs?10%?@APTES nanotubes,the sensitivity increased 23 times and detection limit is 10 ppb,this is the minimum value in the WO₃ nanometer materials,and the most important thing is that the NO₂selectivity is excellent in a mixed environment.The response and recovery time can be up to 11 s and 12 s,respectively.And it has good stability and moisture resistance.Even in 90%of high humidity,it still can reach 80%of the initial response value.In addition,the P-WO₃ NTs?10%?@APTES sensor was applied to the actual enviroment of different air quality for the detection of NO₂ concentration,and the accuracy rate was more than 90%compared to the official data.[3]Using the method of electrospinning prepared different nobel metals doping?Au,Ag,Pt?In₂O₃ NWs.Moreover,the noble metal nanoparticles can be well dispersed in In₂O₃ NWs,and the In₂O₃ have a good crystallization,it can be arranged to the cubic phase crystal.Through reasonable doping,Au/In₂O₃ NWs,Ag/In₂O₃ NWs,Pt/In₂O₃ NWs sensors have excellent gas-sensitive sensor performance than pristine In₂O₃ NWs and the optimum working temperature is300°C.At the optimum working temperature,the linear range and lower detection limit of testing are greatly optimized.The results showed that Au/In₂O₃ NWs had high sensitivity and selectivity to H₂S,and the lower detection limit was 50 ppb.Ag/In₂O₃ NWs has high sensitivity and selectivity to formaldehyde.The lower detection limit is 10 ppb,Pt/In₂O₃ NWs has high sensitivity and selectivity to acetone,and the lower detection limit is 20 ppb.To verify the effectiveness of the three different nobel metals doping gas sensor test result for simulating different disease exhale environment,the result shows that the test of different volunteer breath testing samples,it can accurately distinguish between patients and normal people,it provides a strong theoretical research basis for practical application of expiratory sensor.[4]Using the method of coaxial electrospinning prepared the core-shell Pt@In₂O₃ nanowires,and the internal Pt core and external In₂O₃ shell were successfully prepared depend on the precursor content of regulating internal Pt.The optimum ratio of In/Pt is 10:1 via the demonstration of morphology and structure.The shell thickness of thecore-shell Pt@In₂O₃ nanowire is 27 nm and the Pt core is27 nm.Through the test and analysis of acetone gas,it shows that the response value increased six times than the reference sample.The lower detection limit can reach10 ppb,and the response and recovery time are 14 s and 16 s,respectively.In this case,it also showed high selectivity and stability.These excellent properties can reach the detection standard of diabetes?1.8 ppm?.But particularly high humidity in real exhaled breath,the sensor can't work normally.Through the protection of SBA-15 molecular sieve layer,it can effectively avoid the effect of humidity on the properties of gas-sensing,even at the enviroment of close to 100%relative humidity of environment;the sensor can also keep more than 90%of the initial value.The prepared gas sensor is designed into a mobile device to monitor the clinical samples in real-time detection,and can accurately distinguish the diabetic patients and healthy people.