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Synthesis,Modification Of Indium Oxide Microstructures And Their Gas-Sensing Performance

Posted on:2018-11-12Degree:MasterType:Thesis
Country:ChinaCandidate:M ZhangFull Text:PDF
GTID:2348330536465873Subject:Electronic Science and Technology
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Indium oxide?In2O3?,an n-type semiconductor metal oxide with a direct band gap of 3.55–3.75 eV,has been widely used in the field of gas sensor as a gas sensing material due to its good catalytic activity,high electric conductivity and wide band gap width.In recent years,the researches have been reported that the gas sensing properties of In2O3 gas sensors can be effectively improved by doping.In this dissertation,In2O3 microstructures are prepared by hydrothermal method,and the gas sensing performances are investigated by noble and metal oxide doping.XRD,SEM,EDS,TEM and XPS are introduced to characterize the crystal structures,microtopography,elementary compositions and valence states.Meanwhile,the gas sensing measurements based on the fabricated In2O3 gas sensor were carried out and the analytic conclusions could be obtained as follows:?1?Hollow microsphere structures of In2O3 were synthesized by hydrothermal method,and the characterization results demonstrate that the as-prepared In2O3 samples are cubic crystal structures.The experimental results of gas sensing properties indicate that the response of the gas sensor can reach to 10.3 for 100 ppm isopropanol at the optimum operating temperature?300 ??.Moreover,the response/recovery times are 2 s/7 s,respectively,and the limit of detection is as low as 500 ppb.?2?Au-doped flower-like In2O3 microstructures with different concentrations?0 mol%,1 mol%,3 mol% and 5 mol%?were fabricated and the analysis results demonstrate that there is no obvious influence on the morphologies of the In2O3 microstructures due to the introduction of Au element.The gas sensing experimental results manifest that the Au-doped In2O3 not only reduces the optimal operating temperature?250 ??,but also improves the gas sensing performance of the gas sensor.Especially,when the molar ratio of Mo/In is 3%,the gas sensing maximum response can reach to 23.1 for 100 ppm acetone.?3?Pure and Mo-loaded In2O3 microstructures with different concentrations?1 mol%,3 mol% and 5 mol%?were prepared and the gas sensing performances of gas sensor to ethanol were investigated.The experimental results demonstrate that the response of In2O3 gas sensor with 3 mol% contents of Mo?Mo3In?can reach to 7 for 100 ppm ethanol,which is about 1.8 times that of the pure In2O3?Mo0In?gas sensor.Moreover,the addition of Mo element can also improve the performance parameters such as response/recovery time,selectivity,stability and so on.Meanwhile,The discussions about gas-sensing mechanism of gas sensor demonstrate that noble metal?Au?doping not only enhances the conductivity of materials,but also can improve the gas sensing performance of the sensor as a catalyzer;The heterojunction can forms due to introduction of the common metal oxide,resulting in the broaden of the depletion layer width and the improvement of the gas sensing properties.
Keywords/Search Tags:Indium oxide, Hydrothermal method, Au doping, Mo doping, Sensor, Gas sensing properties
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