Synthesis Of In₂O₃ Nanostructured Materials And Study On Gas Sensing Properties

Metal oxide semiconductor gas sensor for its easy to carry,small size,low production cost,simple operation and other advantages in the actual production and life has been used widely.Metal oxide-based semiconductor gas-sensing materials have also been developed rapidly.Such as weather monitoring,disaster emergency treatment,greenhouse gas emissions,food and drug inspection,quarantine environmental resources survey,industrial production safety warning early and process control,geological mineral exploration and other fields.The gas sensing properties of gas-sensitive materials with different morphologies and the gas-sensing principle of gas-sensitive materials with different morphologies have become a hotspot in the field of gas-sensing materials in recent years.Nanocubes,nanowires,nanosheets,nano-hollow microspheres and core-shell structures.Metal oxide In₂O₃ is a structurally stable n-type semiconductor compound and has good electrochemical and optical properties.In this paper the In₂O₃ products with different morphologies Zn-doped In₂O₃ products and Sn-doped In₂O₃ products were synthesized by adjustion the ratio of surfactants under the same conditions of reaction temperature,reactant concentration and operation method.No literature report the way of this paper.And the gas-sensing properties of products were explored.Trying to get the relationship between the synthetic conditions and the different morphologies,the relationship between the detection value of gas formability and the selectivity of gas sensitivity,the relationship between the detection value of gas sensitivity and the test temperature.To this end of this paper has achieved the following results1.In hydrothermal system of low temperature with different morphologies of In₂O₃ powder were synthesized by adjustion the ratio of polyacrylic acid（PAA）and sodium dodecyl sulfonate（SDS）.Morphologies of cubic,flower and spherical（including hollow structure）.Without the addition of PAA and SDS,under the conditions of the synthesis of nanocrystalline composed of nanoshort rods formed from the cubic particles,the size of it about 300-500 nm.By changing the PAA and SDS concentration ratio to get flower and spherical particles,particle size is uneven.There is the phenomenon of agglomeration,particle size of it about 1-2 μm.The X-ray diffraction structure analysis and high-resolution projection electron microscopy analysis of In₂O₃ samples were carried out.The samples with different morphologies of In₂O₃ were cubic crystal.X-ray photoelectron spectroscopy analysis shows that the cubic morphology of In₂O₃ powder has more chemical adsorption of oxygen.The gas-sensing properties of nitromethane,xylene,toluene,benzene and formaldehyde were investigated for different morphology samples.It was found that the cubic In₂O₃ material obtained at calcination temperature of 400 ° C had a working temperature of 100 ° C,a nitromethane response time of 1-2 s,sensitivity response value higher than 600.In low temperature environment,the rapid detection of flammable and explosive nitromethane gas showed good selectivity.2.On the basis of the synthesis conditions of pure In₂O₃ nanopowder,the element Zn and Sn doping and the molar ratio were 2%.The morphology of the composites was controlled by adjustion the ratio of PAA and SDS.The morphology of the synthesized products showed cubic,flower and spherical（including hollow structure）.The morphology of the synthesized Zn and Sn doped particles was flower in the form of PAA concentration of 1 g/L and SDS concentration of 1 mmol/L,while the morphology of the synthesized product was spherical in the pure In₂O₃ system.In the structural analysis and elemental analysis of the samples,it was found that the crystal form of Zn and Sn doped In₂O₃ products was cubic.In high resolution transmission element mapping and EDS energy spectrum were determined by element doping into the crystal.When the working temperature is 150 ° C,the sensitivity of the Zn,Sn doped In₂O₃ product to xylene is higher than that of the pure In₂O₃ system.The response time is 1-2s.