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Rational Design And Gas Sensing Properties Study Of Metal Oxide Semiconductor Materials

Posted on:2021-04-19Degree:DoctorType:Dissertation
Country:ChinaCandidate:T Y WangFull Text:PDF
GTID:1368330623477125Subject:Condensed matter physics
Abstract/Summary:PDF Full Text Request
Metal oxide semiconductor based gas sensors have become a hot spot in sensor research because of its excellent performance,simple structure,low cost and good compatibility with other equipments.The main parameters of gas sensing performance of metal oxide semiconductor based gas sensors include sensitivity,selectivity,response/recovery speed and operating temperature,among which the response/recovery speed is one of the important indexes to measure the performance of gas sensors.How to improve the response and recovery speed of gas sensing materials to target gas is the key to realize rapid disease detection,timely warning of hazards and industrial safety production.To speed up the response/recovery rate of gas sensing materials,it is necessary to improve gas diffusion,gas adsorption/desorption during the gas sensitive process and promote the reaction between the chemisorbed oxygen ions on the surface of sensing materials and the target gas.Therefore,we need to design and construct gas sensing materials with specific structures,such as hollow structure,mesoporous structure,hierarchical structure and so on,to facilitate the diffusion,adsorption and desorption of gas molecules,or the introduction of p semiconductor with catalytic activity to accelerate and enhance the surface chemical reaction.Based on the above discussion,we take some typical metal oxide semiconductors as the research object.As constructing high performance gas sensing materials through morphology regulation and electronic structure regulation,in-depth study will establish the relationship between the physical properties of sensing materials and gas sensing properties,reveal the key factors and promotion principle of enhancing gas sensing properties and explore gas sensing mechanism.The following results are obtained.?1?Based on morphology control,SnO2 hollow mesoporous cubes with triple-shelled layersare constructed by"coprecipitation-annealing-etching"strategy,which greatly increases the surface area of sensing materials.Meanwhile,SnO2hollow cubes with single-and double-shelled structures are introduced to study the influence of different shell layers on toluene gas sensing properties.Gas sensing tests indicate that the synergistic effect of the hollow structure,mesoporous structure and three-dimensional cube greatly improve the gas permeation,diffusion,adsorption and desorption processes,and then the sensing materials show a faster response/recovery rate?0.8 s/6.1s?.?2?Based on the structure design,Cu2O hollow hexapod tubular structures are synthesized by an environmental friendly strategy.Their growth mechanism and gas sensing properties are investigated in detail.Cu2O hollow hexapodtubular structures based gas sensors exhibit an enhanced gas sensing performance to 100 ppm trimethylamine gas at 220 oC in terms of high sensitivity,rapid response/recovery speed?2.1 s/8.8 s?and superior stability and repeatability.The internal and external surfaces of three dimensional hollow hexapod tubular structures participate in gas adsorption/desorption and surface chemical reaction,improving material utilization and making sensing materials show enhanced gas sensing properties.?3?Based on electronic structure adjustment,deposit p-type chromium oxide?Cr2O3?nanoparticles on the surface of flower-like zinc oxide?ZnO?assembled from nanosheets,form Cr2O3-ZnO p-n hierarchical heterostructures.The favorable gas diffusion,gas adsorption/desorption produced by three dimensional hierarchical structure,a wider electron depletion layer introduced by p-n heterojunction and the catalytic effect of p semiconductor Cr2O3 on the target gas effectively accelerate the gas sensing kinetics of Cr2O3-ZnO p-n hierarchical heterostructures.
Keywords/Search Tags:Metal oxide semiconductor, Gas sensor, Performance regulation, Response/recovery rate
PDF Full Text Request
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