【作者】 李本侠；

【导师】 谢毅；

【作者基本信息】 中国科学技术大学 ， 无机化学， 2008， 博士

【摘要】 本论文发展了液相化学合成与同步组装的方法,提出了一系列合成三维分级结构的新思路,并在合成金属氧化物和硒化物功能纳米材料的实践中取得了重要进展。其中通过调控实验参数来控制晶体生长模式制备了一系列的PbSe和CdSe三维分级结构;利用前驱物模板热转化法获得了Co₃O₄三维分级组装结构;设计了一种新颖的囊泡模板界面反应路线,通过软模板诱导实现了以纳米立方块为构筑单元组装成的In（OH）₃空球,并通过热解获得In₂O₃空球结构;利用产物晶体生长的各向异性,发展了一种简单有效的自生成模板诱导组装路线实现了空心海胆状α-MnO₂分级结构的合成。本论文的主要内容归纳如下:1.作者利用溶液相化学合成与同步组装的方法,通过调节反应参数来控制反应体系中Se^2-的产生速率,从而控制硒化物的成核和生长速度,获得了PbSe和CdSe材料的一系列微米/亚微米三维多级结构:（a）通过选用不同的硒源在丙三醇-水混合溶液体系中合成出两种不同三维形貌的PbSe微晶。其中,以SeO₂作硒源、水合肼作还原剂合成出了具有对称性的多级树枝状结构;以Se粉作硒源不使用还原剂则合成出骰子状PbSe微米结构。对此,我们提出了相应的形成机理。（b）我们通过调节反应体系中氨水（25%NH₃）的加入量获得了棒状、穗状以及管簇状的CdSe亚微米组装结构;其中氨在合成体系中扮演双重角色:为Se^2-的形成提供碱性环境并为Cd²⁺提供配体。这种合成方法为制备CdSe半导体材料的组装体提供了一种操作简单、反应温和且重复性好的途径。2.作者利用前驱物模板热解的方法实现了无机纳米材料的定向合成与组装。利用前驱物和目标产物的结构特点,通过选择、合成适当的前驱物作为模板并经热转化获得了目标产物的纳米组装体。我们利用钴盐（CoCl₂·6H₂O）和尿素在不同温度下（100℃,140℃和180℃）的简单水热反应合成出三种新型碱式碳酸钴的组装结构;然后以碱式碳酸钴的组装结构为前驱物模板,通过在空气中加热裂解,获得了相应的Co₃O₄的三维有序分级组装结构。3.作者设计了一种新颖的囊泡模板界面反应路线,通过软模板诱导实现了以纳米立方块为构筑单元组装成三维空球结构:即在“甲酰胺-间苯二酚-水”反应体系中通过反应过程中生成的囊泡模板的诱导作用,获得了由单晶纳米立方块组装成的In（OH）₃空心微球。随后,通过在空气中热处理In（OH）₃空球样品,我们还获得了In₂O₃空心微球,且In₂O₃空心微球样品显示出了良好的光催化活性和气体敏感性。4.作者利用产物晶体生长的各向异性,发展了一种简单有效的自生成模板诱导组装路线,在不使用任何外加模板和表面活性剂的条件下,实现了一维纳米结构在三维空间的自组装。在溶液相中温和还原的反应路线和低温晶化相结合获得了大量的空心海胆状α-MnO₂纳米组装体,并且通过对不同反应阶段产物的结晶性和形貌演变的监测证实了空心海胆状α-MnO₂纳米组装体的形成机理。这种特殊结构的α-MnO₂纳米材料作为锂离子电池的电极材料表现出了良好的电化学性质。更多还原

【Abstract】 In this dissertation, a series of new chemical routes were developed for the synthesis and assembly of various 3D hierarchical structures. Various hierarchical structures of PbSe and CdSe were synthesized by adjusting the manner of crystal growth in the solution-based reaction systems. Co₃O₄ hierarchical structures were rationally prepared by the pyrogenation of the as-obtained precursor templates. In（OH）₃ and In₂O₃ hollow microspheres constructed by nanocubes were achieved with assistance of the soft template. Hollowα-MnO₂ hierarchical microspheres were obtained, based on the anisotropic growth of the product’s crystal and the self-generated template route. The details are summarized briefly as follows:1. The author developed the solution-based chemical synthesis and simultaneous assembly routes to synthesize various submicrostructures of metal selenide semiconductors by controlling the producing rate of Se^2- in the reaction systems, which determined the nucleation and growth of the product’s crystal. （1） Well-crystalline PbSe multiple-dendritic hierarchical structures and cuboidal microcrystals were controllably synthesized by choosing different Se source in an alkaline glycerol/water solution system. The possible growth mechanisms for the two kinds of PbSe microstructures were proposed from the point of crystallographic and kinetic views. （2） A series of CdSe submicrostructures, including rods, fringy structures, and fasciculate tubes with high hierarchy, have been selectively prepared by simply changing the feeding quantity of aqueous ammonia （25% NH₃）. Ammonia in the reaction system plays a dual role: providing an alkaline medium for the formation of Se^2- and acting as a coordinating agent for Cd²⁺ . This concise and novel one-step route has special advantages, suggesting a new path for convenient synthesis of CdSe materials with novel morphologies.2. The authors developed the precursor-template pyrolysis method to achieve the synthesis and assembly of inorganic nanomaterials. Based on the structural characteristics of the precursor and the target product, the hierarchical structures of the target product were obtained through the pyrolysis of the as-prepared precursor-template. Highly uniform 3D sisal-like, dandelion-like and rose-like architectures of cobalt hydroxide carbonate were synthesized through a facile hydrothermal process at 100℃, 140℃and 180℃, respectively. Subsequently, Co₃O₄ superstructures with the corresponding morphologies were obtained by the pyrolysis of the as-prepared precursors.3. The authors designed a novel vesicle-template-interface route to assemble the three-dimensional hollow microspheres by the inducement of soft template. In（OH）₃ hollow microspheres constructed by numerous nanocubes were successfully prepared in the "formamide-resorcinol-water" system. As desired, InO₃ hollow microspheres were obtained from annealing the designed In（OH）₃ hollow structures, and the as-obtained InO₃ hollow microspheres performed well as a gas-sensing material in response to both ethanol and formaldehyde gases and as a photocatalyst for photocatalytic degradation of rhodamine B.4. Based on the anisotropic growth of the product’s crystal and the self-produced template route, we successfully realized the assembly of one dimensional nanostructures into three dimensional hierarchical hollow microspheres. Novelα-MnO₂ hollow urchins were synthesized on a large scale by a facile and efficient mild reduction route, without templates or surfactants in the system. The formation mechanism for the hollow urchins was proved to be the Ostwald ripening process by tracking the crystallization and morphology of the products at different reaction stages. Theα-MnO₂ hollow urchins exhibited good chemical property when used as the cathode material in Li batteries. This synthetic procedure is straightforward and inexpensive and thus facilitates the mass production ofα-MnO₂ hollow hierarchical structures.更多还原