【作者】 程知萱；

【导师】 张建成；

【作者基本信息】 上海大学 ， 材料学， 2008， 博士

【摘要】 纳米材料和结构是当今材料领域中十分重要的研究对象,特别是其新颖的物理、化学和生物学特性以及在纳米器件中的应用已成为当今纳米技术的研究热点。如何控制材料的定向生长并实现对其尺寸、维度等形貌的调控,对于深入研究材料形貌与物性间的关系,最终实现按照人们的意愿设计制备功能材料具有重要的意义。本论文采用液相法,在氧化铟（In₂O₃）材料的形貌可控制备与其特征研究方面作了有益探索。通过选择合适的形貌控制剂,可控制备了不同形貌的In₂O₃材料,包括一维的纳米棒、纳米线,以及介孔结构等,并详细考查了反应条件对产物形貌的影响。根据材料结构表征,初步探讨了不同结构氧化铟纳米材料的生长机理。并将不同形貌的纳米氧化铟制成旁热式气敏元件,测试了元件的气敏性能,通过与纳米颗粒氧化铟进行比较,探讨了气敏材料的结构、形态与气敏性能的关系。本论文主要成果如下:1.以氯化铟和氨水为原料,非离子表面活性剂壬基酚聚氧乙烯醚（OP-10）为形貌控制剂,通过控制反应条件,成功制备出一维In₂O₃纳米棒（直径约20 nm,长度在120 nm左右）。对其纳米棒生长的影响因素研究表明:反应温度是影响纳米棒长度的主要因素,而形貌控制剂浓度则会影响棒的分散性。对其形成机理探讨认为:OP-10的分子几何排列参数在1/3～1/2范围内,可以形成棒状胶团,依据这一原理,以OP-10棒状胶团为模板,控制制备了棒状结构的In₂O₃。2.对一维氧化铟纳米棒气敏性能测试结果表明,In₂O₃纳米棒在130℃时对三甲胺（Trimethylamine:TMA）有较高的灵敏度和选择性;对酒精、甲醇、丙酮、甲醛等气体在260℃处有较好的灵敏度;对氢气在较高温度（＞350℃）时有较高的灵敏度和选择性;材料对氨气和丁烷基本不响应。气敏机理初步探讨认为,具有较强供电子能力的TMA是In₂O₃纳米棒气敏元件在较低温度下对TMA有高的灵敏度和选择性的主要原因。3.将一维棒状纳米In₂O₃与零维颗粒状纳米ZnO、SnO₂和In₂O₃按5wt.%的质量百分比复合,通过控制烧结工艺条件,首次制备出具有多孔架空结构的多维复合纳米棒In₂O₃材料。气敏性能测试结果表明:具有多孔架空结构的多维复合纳米棒材料能够有效改善材料的气敏性能,不仅明显提高了对测试气体的灵敏度和选择性,还可以降低元件的工作温度;特别是对TMA显示出良好的气敏性能,为开发高灵敏度高选择性TMA传感器提供了可能。对多维复合材料的气敏机理分析认为,在纳米尺度下的多孔架空结构能够增大材料的有效比表面积,形成吸附反应的载体,为气体吸附提供了较大的立体空间,因此能够有效地提高材料的气敏性能。4.采用三嵌段共聚物PE6800作为形貌控制剂,通过超分子自组装,在室温、水溶液中成功制备出平均孔径在6nm左右,BET比表面积54.8m²·g^-1,吸附孔容为0.345cm³·g^-1的介孔结构In₂O₃粉体,并研究了形成介孔氧化铟的影响因素。对介孔In₂O₃的气敏性能测试结果表明,元件对甲醛、乙醇、甲醇、NO₂等气体具有较高的气体灵敏度,尤其是对乙醇气体表现出高的灵敏度和良好的响应-恢复特性,有望用于对乙醇气体的检测。论文探讨了制备温度、孔结构对介孔In₂O₃气敏性能的影响,认为低的制备温度有利于气体灵敏度的提高;与颗粒状纳米氧化铟的气敏性能比较,证明介孔结构的In₂O₃的灵敏度确实要比颗粒状的纳米In₂O₃高,如对乙醇和H₂的灵敏度可提高20%多。5.采用水热-前驱体热分解法,以草酸为一维结构导向剂,控制制备出高长径比的In（OH）₃纳米线（长径比＞40）,通过优化热处理条件制得In₂O₃纳米线,该纳米线直径为30～50nm,长度达到2μm以上。对In₂O₃纳米线的气敏性能研究结果表明:该In₂O₃纳米线对NO₂气体具有灵敏度高（5 ppm时,灵敏度可达9.6）、选择性好（不受众多还原性气体的干扰）、检测下限低（可检测1 ppm的NO₂）以及响应恢复快等优点,在环保、汽车尾气监控等方面具有良好的应用前景。更多还原

【Abstract】 Nanomaterials and nanostructures are very important research target in present fields of materials,especially they have become research hot spot in fields of nanotechnology nowdays because of their novel physical,chemical,biological characteristics and novel potential applications in nanometer devices.For the synthesis of nanomaterials,liquid-phase method has been widely used in the preparation of nanoparticles because it is easy to control nucleation,uniform composition and component,and can be obtained high purity nano-oxides.In this paper,In₂O₃ nanostructures,including nanorods,nanowires,and mesoporous morphology and structure were prepared by liquid-phase method with different surfactants.The morphology and structure of the materials synthesized were characterized.Various reaction parameters,such as morphological controlling agents, reaction temperature and time,were studies in this work.The growth mechanism of In₂O₃ with different nanostructures was discussed.The gas-sensing properties of In₂O₃ with different morphology were studied by using the side-heated gas sensors.The relationship between structure of In₂O₃ materials and gas-sensing properties was discussed.Main achievements of this paper:1.In₂O₃ nanorods were prepared by controlling the kinetics parameters in reaction process and using polyethylene octyl phenyl（OP-10） as a controlling agent of morphology,InCl₃·4H₂O and ammonia as the raw materials.The results indicated that In₂O₃ nanorods had the length of about 120nm and the diameter of about 20nm.Studies on the factors influencing growth of In₂O₃ nanorods showed that reaction temperature played a key role in controlling the length of In₂O₃ nanorods,and the concentration of morphological controlling agents affected the dispersion of nanorods.Discussion of the formation mechanism showed that the geometric arrange parameter of OP-10 was in 1/3-1/2,it could form claviform micelle.So at the appropriate reaction temperature and concentration,In₂O₃ nanorods were prepared. 2.The gas sensing properties of In₂O₃ nanorods were measured by mixing detected gas and air in static state.The testing results showed that In₂O₃ nanorods had higher sensitivity and selectivity to trimethylamine（TMA） at 130℃;good sensitivity to C₂H₅OH,CH₃OH,CH₃COCH₃,HCHO at 260℃but low selectivity;higher sensitivity and selectivity to H₂ at much higher temperature;then little response to NH₃ and C₄H₉. The analysis of gas-sensing mechanism was indicated that In₂O₃ nanorods had higher sensitivity and selectivity to trimethylamine at low temperature due to its strong ability to supply electrons.3.Multi-dimensional compound In₂O₃ materials with porous overhead structure were first prepared by dopping In₂O₃ nanorods with 5wt.%ZnO,SnO₂ and In₂O₃ nanoparticles and controlling the sintering conditions.The results of gas-sensing test showed that multi-dimensional compound In₂O₃ materials could improve the sensitivity and selectivity,and decrease the power consumption;especially had good response to trimethylamine which make it possible to develop trimethylamine sensor with high sensitivity and selectivity.Analysis of gas-sensing mechanism for the compound showed that porous overhead structure could enlarge effectively specific surface area,and form support of adsorption reaction,overcome resistance of eiectronic migration so it could improve gas sensing properties.4.Mesoporous indium oxide were prepared by simple sol-gel technique with three block copolymer PE6800 as a agent of controlling their morphology,H₂O as a solvent and indium chloride as a precursor.The decomposition process,crystal structure and micro-morphology of samples were characterized by TG-DSC,XRD,SEM,TEM and BET.The influence factors of forming mesoporous In₂O₃ were discussed.The results of gas-sensing test showed that In₂O₃ nanorods had good sensitivity to C₂H₅OH, CH₃OH,HCHO,NO₂;especially except for good sensitivity to C₂H₅OH and had better response-recovery properties,so they were promising to be used in C₂H₅OH detection. The effects of reaction temperature and porous structure on gas-sensing properties were discussed.Compared with In₂O₃ nanoparticles,we found that gas response of the sensor based on mesoporous In₂O₃ materials was higher than that of In₂O₃ nanoparticles.5.In₂O₃ nanowires with high aspect ratios（＞40） were synthesized via hydrothermal-annealing route.The gas-sensing measurement showed that the sensor based on In₂O₃ nanowires had excellent gas-sensing properties to NO₂ which make it favorable to be used in environmental protection,exhausting gas monitor and so on.更多还原