Doping Modification And Sensing Properties Performances Of Indium Oxide Nanomaterials

With the social development and progress,human beings are facing more and more serious problems such as global warming,air pollution.It is urgent to monitor and control gases in specific occasions and environments.Therefore,the research and development of gas sensors with excellent performance and meeting specific needs has attracted extensive attention of domestic and foreign researchers.Among many kinds of gas sensors,resistance semiconductor oxide gas sensor has become a research hotspot in the field of gas sensing in recent years because of its high sensitivity,strong stability,good selectivity,miniaturization,easy operation and low cost.The performance of gas sensors is related to the morphology,microstructure and surface properties of sensitive materials.How to develop sensitive materials with suitable microstructures and high surface activity is of great significance to improve the performance of gas sensors.Indium oxide?In₂O₃?,as an important N-type metal oxide semiconductor,has a bandgap of 2.8eV,high conductivity and catalytic activity,and has important application prospect in the field of gas sensing.Important progress has been made in the research of In₂O₃-based gas sensor,the sensing performance of In₂O₃sensor must be further improved in order to meet the actual needs.In this paper,In₂O₃sensitive materials with specific morphologies and microstructures were synthesized by hydrothermal method,and their gas sensing properties were effectively improved by doping.By changing reaction temperature,selecting precipitant,optimizing precipitant dosage and screening surfactants to change the morphology and micro-nanostructure of In₂O₃,the hierarchical flower-like microspheres and hollow spheres of In₂O₃ sensitive material were prepared.Using structural advantages,the structure sensitization was realized.Meanwhile,different metal oxides were doped into the pure In₂O₃ material to further enhance the gas sensing properties,realizing the modification sensitization.The main research contents are as follows:Combining the advantages of hierarchical structure and doping modification function,an excellent acetone gas sensor was prepared.Flower-like microspheres with hierarchical structure of In₂O₃ were synthesized by hydrothermal method with the help of surfactant to control the morphology.In-situ Ce doping technology was used to further improve its gas sensing properties.The results of gas sensing test show that the doping amount of Ce affects the gas sensing properties of In₂O₃.At 250oC,the sensitivity to acetone gas at 200 ppm is 41.8,about four times than pure-phase In₂O₃gas sensors in the same environment.The results show that Ce doping significantly improves the acetone sensitivity of In₂O₃.Using various characterization techniques,the correlation between grain size,resistance value,amount of adsorbed oxygen on the surface and the improvement of gas sensing properties was analyzed.The improvement of gas sensing properties of In₂O₃ by Ce doping can be attributed to the larger specific surface area,lower carrier concentration and good permeability of the microstructures.Therefore,Ce doping is significant in recognition function and utilization ratio of the sensitive body to improve the sensing performance of gas sensors.La-doped In₂O₃ hollow spheres were synthesized by one-step hydrothermal method.The results of gas sensing test show that the prepared material's response to H₂S gas is obviously improved,the 3.0 mol%La–doped In₂O₃ exhibited the highest response toward 10 ppm hydrogen sulfide?H₂S?at 200oC,having a response value of17.8,4.8 times higher than pure In₂O₃.Furthermore,excellent selectivity,good repeatability and outstanding long-term stability of the gas sensor also achieved.The XPS?XRD and BET characterization techniques suggest that the improvement of gas performance is mainly due to the increase of defect oxygen and chemisorbed oxygen,the decrease of grain size and the increase of specific surface area caused by La doping.