【作者】 殷竟洲；

【导师】 陆轻铱； 高峰；

【作者基本信息】 南京大学 ， 无机化学， 2011， 博士

【摘要】 金属氧化物及复合氧化物纳米材料具有丰富的物理化学性质,是材料科学和材料化学的重要研究对象,在诸多领域有着广泛的应用。由于晶体存在各向异性,决定了晶体中不同的晶面或取向会表现出不同的物理和化学性质。因此,控制合成不同形貌及组装方式的金属氧化物及复合氧化物纳米材料,进一步调控其物理和化学性能,提高其在光、磁及催化等方面的性能,对于基础科学研究和技术应用都有着重要的意义。本文在水(溶剂)热条件下,将纤维素基高分子表面活性剂引入到反应体系中,合成了一系列形貌新颖的金属氧化物及复合氧化物纳米材料,并通过调节反应条件,实现了对其形貌的控制。通过相关的表征及性能研究,对纳米材料的形成机理、形貌与性能之间的关系进行了有益的探索。主要研究内容如下：1.高度有序的自组装纳米结构可能具有新颖的性能,在羧甲基纤维素纳(CMC)存在的条件下,成功合成了由纳米棒组装的中空氧化锌(ZnO)笼状超结构。通过改变反应条件,ZnO中空笼状超结构可从单个笼,双笼,多个笼和相连的笼进行调节,并提出了可能的形成机理。并研究了不同ZnO笼状超结构催化分解高氯酸铵(AP)性能,结果表明,所有的笼状超结构都有很好的催化分解AP的活性,其中以单头笼状超结构催化性能最好。2.天然高分子表面活性剂CMC,不仅可以作为晶体生长调节剂,还可作为反应物参与反应。利用KMnO4和CMC发生的氧化还原反应,通过改变反应条件(反应物摩尔比、反应温度和反应时间),合成了一系列的锰基纳米结构如：八面体Mn3O4, MnOOH纳米棒,MnO2纳米线和梭状的MnCO3纳米颗粒聚集体。并研究八面体Mn3O4纳米粒子的直接电化学性质,结果表明八面体Mn3O4可以有效地促进细胞色素c在电极表面的电子传递。3.高指数晶面具有较高的表面能,可能具有高反应活性或特殊的物理和化学性质。我们在高分子表面活性剂CMC水溶液中成功地制备了具有高指数暴露面的十四面体和斜平行六面体氧化铁纳米晶。磁性研究表明这两种纳米晶有着不同的磁学性质。十四面体氧化铁纳米晶在室温下表现为自旋斜交的铁磁性主导,而在Tm温度以下铁磁性消失。斜平行六面体纳米晶在室温下表现为自旋斜交的铁磁性和缺陷型铁磁性共存,而在低温下是缺陷型铁磁性主导。4.自组装的纳米结构,由于具有特殊形貌和结构,而赋予纳米材料新颖的物理和化学性质。将CMC作为生长调节剂引入到反应体系中,合成了新型分级鼓状氢氧化镉(Cd(OH)2)超结构。Cd(OH)2鼓状超结构是由若干多面体单元聚集而成,这些多面体单元是不完整的六角双锥金字塔结构。通过分析相关实验结果,提出了这种鼓状Cd(OH)2超结构可能的形成机理。通过高温焙烧得到氧化镉(CdO)超结构,并能够保持形貌。催化性能研究表明,Cd(OH)2和CdO超结构都具有较好的催化分解AP活性。5.纳米材料的物理和化学性质与暴露晶面密切相关,合成具有不同暴露晶面的晶体对进一步研究其性能具有重要意义。在甲基纤维素(MC)存在条件下,利用溶剂热法,通过改变反应体系中NaOH的物质量,成功合成了具有不同暴露面的ZnSnO3多面体,包括六面体、削角六面体、十四面体、削角八面体及八面体。6.其他相关工作。采用简单的溶剂热法,用生物分子甘氨酸辅助合成ZnO纳米结构,通过调节溶剂中水和乙醇的比例,调控合成了具有不同形貌和组装方式的ZnO微/纳结构,并研究不同形貌的ZnO催化及光致发光性能；通过简单的液相法,无需任何表面活性剂存在条件下,通过调节反应条件,控制配合物晶体生长,得到形貌均一的球状和线状金属钴与乙酰丙酮和肼的配合物纳米结构。更多还原

【Abstract】 Metal oxide and complex metal oxide nanostructures have exhibited great application potentials, and become a popular research subject in materials chemistry. Single crystals have a basic property of anisotropy and exhibit different physical and chemical properties on various facets or in diverse directions. Therefore, it is believable that the controllable synthesis of metal oxide and complex metal oxide nanostructures with different morphologies and assembling behaviors to further tune their chemical and physical properties will benefit the improvement of their optical, magnetic and catalytic properties for basic research and technology applications.In this thesis, a series of novel metal oxide and complex metal oxide nanostructures have been synthesized through hydro-/solvo-thermal approaches in the presence of cellulose-based polymeric surfactants. The morphologies of these nanostructures were successfully controlled by changing the reaction conditions. The properties of the nanomaterials were studied and the relationship between the properties and morphology of the nanomaterials were discussed. The main contents of our work are summarized as follows:1. Self-assembled structures with highly specific morphology could bring brand-new properties. Hierarchically complex hollow cage-like ZnO superstructures assembled by nanorods have been successfully constructed in the presence of sodium carboxymethyl cellulose. The number of the hollow cage could be adjusted from single-cage, double-cage, multi-cage to connected-cage. A possible formation mechanism of the hollow superstructures has also been proposed. The catalytic properties on the decomposition of AP of the various ZnO superstructures have been studied. The results showed that all the superstructures have good catalysis properties, and the single-cage superstructures show enhanced activity over other multicage superstructures.2. The CMC, a kind of water-soluble polymer, is not only reactant but also crystal growth modifier. By adjusting the experiment conditions such as the molar ratio of the reactants, the reaction temperature, and the reaction time, several manganese-based (with the Mn oxidation states from+2to+4) nanostructures including Mn3O4octahedrons, MnOOH nanorods, MnO2nanowires and aggregated MnCO3nanoparticles in the form of spindles can be obtained through the redox reaction between KMnO4and CMC. The study of the direct electrochemical behavior of cytochrome c (Cyt. c) immobilized on octahedral Mn3O4modified glassy carbon (GC) electrode shows that the octahedral Mn3O4nanoparticles could promote the direct electron transfer between Cyt. c and the electrode.3. Because high-index facets usually have high surface energy, these facets can endow nanocrystals with high catalytic activities or bring brand-new properties. We report for the first time two kinds of iron oxide crystals in the hexagonal crystal system:tetrakaidecahedra and oblique parallelepipeds with high-index facets exposed. Owing to the fact that iron oxide belongs to the hexagonal system, these exposed high-index facets are very special, and the two kinds of brand-new polyhedra have never been reported before. Magnetic studies uncovered that these two forms of iron oxide have distinct differences. The tetrakaidecahedral iron oxide nanocrystals might be spin-canted ferromagnetically controlled at room temperature, and the ferromagnetism disappears at temperatures lower than Tm. The oblique parallelepiped nanocrystals might have coexistent spin-canted and defect ferromagnetism at room temperature and be defect ferromagnetically controlled at low temperature.4. Inorganic crystals with highly specific morphology by a self-assembling process may have brand-new properties. Hierarchically novel drum-like Cd(OH)2superstructures have been successfully obtained. The drumlike superstructures are accumulated by numerous polyhedral units, and the polyhedral unit is an incomplete structure of a double hexagonal pyramid. A possible formation mechanism of the drum-like Cd(OH)2superstructures has also been proposed. The as-prepared Cd(OH)2could be transformed into CdO superstructures by calcining in air. These Cd(OH)2and CdO superstructures have been demonstrated to have good catalytic properties to decrease the decomposition temperature of ammonium perchlorate.5. Surface-dependent physical and chemical properties are very important in crystals, which makes it very important to control exposed surfaces of a functional material. The polyhedral ZnSnO3crystals with different exposed facets have been prepared successfully in the reaction system of methylcellulose alcohol solution via a solvothermal method. Simply by adjusting the amount of the added NaOH in the reaction system, the polyhedral crystals include hexahedron, truncated hexahedron,14-faceted polyhedron, truncated octahedron, and octahedron can be obtained.6. Other relevant work. Various ZnO with various distinct morphologies have been successfully synthesized via a simple double-solvent thermal method in the presence of glycine. The morphologies of the products can be successfully controlled from superstructures to microplates by adjusting the amount of water in the EtOH/H2O system. The catalytic properties on the decomposition of AP and photoluminescence properties of the various ZnO superstructures have been studied.Cobalt ion-based coordination nanostructures have been synthesized by using acetylacetone and hydrazine as chelating agents by a simple solution-based method in the absence of surfactant. The morphology of products can be controlled from spheres to nanowires by adjusting the reaction temperature and time.更多还原