Study Of Construction And Gas-sensing Properties Of In₂O₃ Based Micro-nanomaterials

In this thesis,a series of In₂O₃ micro/nanostructures with different morphologies were synthesized by solvothermal and solution synthesis methods,including 1D hollow rod-like structures,2D flower-like structures,and 3D flower-like structures.In₂O₃-based micro/nanomaterials with surface modification and heterojunctions construction were used to improve gas-sensing properties,and mechanisms of performances enhancement were explored.The main research content of this paper is as follows:1.The study of construction and gas-sensing properties of 1D hollow rod-like In₂O₃-based composites.In₂O₃/CuO composites with uniform size were synthesized by one-step solvothermal method combined with subsequent calcination method with In N₃O₉·x H₂O as indium source and Cu(NO₃)₂·3H₂O as copper source,which showed good gas-sensing performance to triethylamine(TEA).In₂O₃/CuO/PdO hollow rod-like composites with a lotus-root-like of rich pore at the top were obtained by one-step calcination of Pdcomponent loaded on In₂O₃/CuO precursor.Compared with pure In₂O₃ and In₂O₃/CuO composites,In₂O₃/CuO/PdO hollow rod-like structures showed the highest response(308.86),the lowest optimum operating temperature(180?),and the shortest response/recovery time(70/18 s)to100 ppm TEA.The enhanced gas-sensing mechanism of composites can be attributed to the formation of In₂O₃-CuO-PdO heterojunction,the increase of specific surface area,and the significant improvement of the electron transport efficiency at the surface/interface.2.The study of construction and gas-sensing properties of 2D flower-like In₂O₃-based composites.The 2D flower-like In₂O₃ precursors with controllable morphology were prepared by optimized solution synthesis method.Composites with ZIF-8 particles on the surface were synthesized by stirring at room temperature.After calcination at 500?,a series of 2D flower-like In₂O₃/ZnO composites composed of needle-like nanorods were obtained.The research showed that In/Zn-2 sensors had excellent gas-sensing performance to TEA,such as higher response value(188.01),lower working temperature(120?),excellent long-term stability,shorter response/recovery time,and so on.The enhanced gas-sensing mechanism can be mainly due to the large specific surface area,the formation of In₂O₃-ZnO heterojunction,and the unique electron transmission path of In/Zn-2.The log(s-1)and log(c)of In/Zn-2 sample have a good linear relationship in the concentration range of 1-200 ppm,which proved that 2D flower-like In₂O₃/ZnO material had wonderful application prospect for the field of seafood freshness detection.3.The study of construction and gas-sensing properties of 3D flower-like In₂O₃ and its composites.Different 3D flower-like In₂O₃ and its composites were synthesized by one-step solvothermal method and subsequent calcination method,which were mainly divided into the following parts:(1)In₂O₃/?-Fe₂O₃ composites:pure In₂O₃ and In₂O₃/?-Fe₂O₃ composites were obtained by solvothermal method and subsequent calcination method.The introduction of Fe source played an important role in regulating the micromorphology,phase structure,and gas-sensing properties of the samples.For example,In/Fe-2 samples showed excellent gas selectivity,lower optimum working temperature,and higher gas response value to TEA.Its enhanced gas-sensing performance was mainly attributed to the large specific surface area,the formation of In₂O₃-?-Fe₂O₃ heterojunction,and the efficient electron transport mechanism.(2)NiO/In₂O₃ composites:By controlling the ratio of Niand In in the precursor,the micro-morphology and structure of NiO/In₂O₃ composite,prepared using solvothermal method and the subsequent calcination,can be effectively regulated.The results showed that the as-prepared Ni/In-2 sensor exhibited the better gas-sensing properties to TEA at 310?,such as higher gas response value(28.43),supreme gas selectivity,and shorter response/recovery time(31/48 s).The gas-sensing enhancement mechanism was mainly attributed to the synergistic effect of flower-like structures assembled by nanosheets and p-n type heterojunction.(3)NiO/ZnO/In₂O₃ composites:Flower-like Ni/Zn/In precursors were synthesized by designing a novel reaction system and using solvothermal method at 150?.NiO/ZnO/In₂O₃3D flower-like structures with controllable morphology were obtained after calcination at 450^oC.The results showed that the composites exhibited higher sensitivity(77.49)and faster response/recovery time(31/31 s)to TEA at 260?.The gas-sensing enhancement mechanism can be ascribed to the synergistic effect of 3D flower-like structure,porous sheet structure unit,large specific surface area,and NiO-ZnO-In₂O₃ heterojunction.