Microstructural Regulation And Performance Studies Of Indium Oxide Gas-sensitive Composite Materials

Due to its unique physical and chemical properties,indium oxide nanomaterials have broad application prospects in photonic devices,electrodes,high-power transistors,and gas sensors.The use of indium oxide as a matrix material and its doping modification can improve its gas sensitivity.The first is that the element doping will hinder the growth of nano-grains,which can lead to the generation of surface defects and the increase of specific surface area of the material to improve its gas-sensitive performance;The second is that the width of the band gap may be shortened,thereby enhancing the gas-sensing reaction.In this paper,Al-doped indium oxide and Ga-doped indium oxide materials were prepared by simple preparation methods.Combined with a series of characterization methods,morphology,composition and gas-sensing performance of the material were tested.Explored the gas sensing mechanism of the material,the content is as follows:1.In2O3 nanorod doped with different molar ratio Al were synthesized by the uniform precipitation method.The modified material showed a good response to formaldehyde.In2O3/6% Al has a response of 73.58 to 10 ppm formaldehyde at its optimal operating temperature of 100?,which is 4 times of pure In2O3.And it shows good selectivity and stability to formaldehyde.Through X-ray diffraction(XRD),X-ray fluorescence spectroscopy(XRF)and transmission electron microscopy(TEM)characterization found that Al is effectively doped into In2O3 and affects its crystal structure,which changes its morphology.Using specific surface area testing(BET),X-ray photoelectron spectroscopy(XPS),photoluminescence spectroscopy(PL)and ultraviolet-visible diffuse reflection spectroscopy(UV-Vis),it was confirmed that the surface of the material doped with Al has more oxygen defects and increased specific surface area.The increase in the number of oxygen defects can not only shorten the width of the band gap,allowing more electrons to participate in the reaction,but also supply more adsorption sites for oxygen molecules and increase the content of chemisorbed oxygen.The increase of specific surface area also helps the adsorption and further reaction of gas molecules.Hall effect test shows that Al doping improves the carrier mobility,which can increase the gas-sensing reaction rate.As the amount of Al doping increases,the oxygen defect content on the surface of the material gradually increases,and the carrier mobility is accelerated,resulting in enhanced gas sensing performance.However,as the doping amount continues to increase,the oxygen defect content begins to reduce,the carrier mobility decreases,and the gas-sensing performance of the material also decline.In2O3/6%Al has relatively many oxygen defects,large specific surface area and high carrier mobility make it show good gas-sensing performance.2.In2O3 nanometer bulk materials doped with different molar ratio Ga were prepared by hydrothermal method for detecting ethanol.The best working temperature of In2O3 material is 260?,in which the response of In2O3/6%Ga to 100 ppm ethanol is 160,which is twice that of pure In2O3,and it shows good selectivity and stability to ethanol.According to the results of characterization analysis,the In2O3 lattice and the surface oxygen state of the material have changed after being doped with Ga.The decrease of lattice parameter indicates that Ga is successfully doped into In2O3.The increase of oxygen defect content makes the surface of In2O3 contain more chemisorbed oxygen,which can improve the sensitivity to ethanol.In2O3/6%Ga has relatively high oxygen defect content,showing a high response to ethanol.