锰氧化物纳米材料及基于铜、钴的有机—无机杂化材料的合成、表征与性质研究

【作者】 郑德山；

【导师】 孙思修； Pierre RABU；

【作者基本信息】 山东大学 ， 无机化学， 2008， 博士

【摘要】 二十一世纪是材料化学的时代,新材料的诞生会带动相关产业和技术的迅速发展,甚至会催生新的产业和技术领域。材料科学现已发展成为一门跨学科的综合性学科。作为材料科学发展的先导,纳米材料的设计合成,是材料得到进一步研究并推广应用的基础。探索发展纳米材料设计与合成的新途径、新方法,实现对纳米材料的尺寸大小、粒径分布,以及形貌和表面修饰的控制仍然是纳米材料研究的一个热点领域。此外,在新兴领域如纳米技术及生物工程中,不断需要具有不同物理和化学性能的新材料。有机-无机杂化材料将有机物种和无机物种在分子水平上有机的结合,提供了用化学方法同时改变材料的组成和结构的可能性,使材料既具有有机物的特质又具有无机物的性能,是一种非常具有潜力的多功能材料,是化学家和材料学家关心的课题之一。本课题组长期以来在液-液体系与萃取化学、无机材料化学两个方向进行深入研究,在溶液体系中溶液结构、结构与相间传质,以及功能材料的制备方面积累了丰富的经验。本论文在课题组前人工作的基础上,研究寻找新的液相合成体系,控制合成具有特殊形貌的无机纳米材料,为纳米材料的制备、组装、裁剪提供了一条新思路。此外,通过离子交换反应在层状无机材料中引入有机配体从而将无机组分的磁性和有机部分自身的特性,包括发光特性,手性等结合起来,制备出了新颖的有机-无机杂化材料。对于扩充功能材料的液相合成,开发使无机材料和有机材料的功能互补、协同优化的有机-无机复合材料的制备方法研究,为有目的地设计和合成具有特定组成、结构和功能的新型有机-无机杂化材料提供实验基础和理论依据。论文主要工作是利用水热法、前驱体法等多种方法成功地控制合成了各种形貌的无机纳米材料;同时也探索了利用离子交换反应制备有机-无机杂化材料。具体内容如下:1.无机纳米材料的制备、表征及机理研究。（a）在非离子型表面活性剂聚乙烯基吡咯烷酮（PVP K30）作用下,利用简单的合成原料,在温和可行的水热条件下,成功地制得了空心结构的单晶MnO₂纳米管,并分析了表面活性剂在合成纳米管状结构中所起的作用,提出了纳米管状结构的形成机理,认为MnO₂纳米管的形成遵循一个:成核-溶解-各向异性生长-再结晶的生长机理。该研究工作扩大了目前所能获得的纳米管种类并提供了一个不同的,基本的路线去制备其他材料的单晶纳米管。（b）我们以与制备MnO₂纳米管状结构相同的原料,调整反应条件,研究了不同反应物配比在不同反应时间下的水热性质,成功合成了γ-MnOOH多足枝状纳米晶,并结合TEM,XRD,SAED,HRTEM等表征手段分析了γ-MnOOH的生成过程,并对包覆剂聚乙烯基吡咯烷酮对多足枝状纳米晶的生长的影响进行了深入研究;然后进一步用合成的γ-MnOOH作为前驱体,经400℃烧结处理制得β-MnO₂多足枝状纳米晶,丰富了我们的锰的氧化物制备体系。（c）通过一个简单的化学方法成功合成了一种新颖的碟型γ-二氧化锰纳米六方片状结构,该方法以硝酸锰为锰源,氯酸钠作为氧化剂,无需添加任何表面活性剂或有机模板,该种纳米六方片边缘长度约250 nm,厚度只有几十个纳米;使用了TEM,XRD,SEM等技术手段对产品进行了表征,并通过跟踪产品在不同反应阶段的结晶情况和形貌,提出了该种新颖纳米六方片可能的形成机理;另外,使用了超导量子干涉仪磁强计对产品的磁性做了简单的测试和讨论;本研究提供了一种崭新的,简易的合成二维γ-二氧化锰纳米六方片的路线从而扩大了可供选择使用的MnO₂范围。2.有机-无机杂化材料的制备与特性研究。（a）通过一种简单、快速的方法以乙醇和水为混合溶剂合成了层间距为1.282 nm的层状水合三羟基醋酸合钴化合物:Co₂（OH）₃（CH₃COO）·H₂O,结合元素和热重分析,得出该种薄层的片状聚集体的化学计量式为Co₂（OH）_3.3（CH₃COO）_0.7·2H₂O;其无水结构也可很容易地得到,只需在120℃进行适当加热一小时;由于层状水合三羟基醋酸合钴化合物所呈现的磁性特性使得其在离子交换反应领域具有重要的地位,同时也使得该种简单有效的合成方法对于有机-无机杂化材料的制备具有重要的意义。（b）通过离子交换反应将手性有机配体分别嫁接到层状羟基醋酸铜和羟基醋酸钴中,此外,还运用了粉末衍射、红外、紫外光谱、扫描电镜以及磁性测量等各种技术手段对产品进行了表征,对这些杂化材料的结构进行了研究并在此基础上对嫁接了有机手性citronellic acid的无机层的磁性行为进行了讨论。更多还原

【Abstract】 The 21st century is the era of chemical materials.The new materials will lead to the rapid development of technology and the related industries,and even lead to new industries and technical fields.Materials science has become an interdisciplinary comprehensive discipline.As a forerunner of the materials science development,the design and synthesis of nano-materials are the foundation of the application and the further development of materials.It is still a hot research field for materials that how to develop new methods to design and synthesis of nano-materials and how to realization the control of nano-particles size,distribution,morphology and surface modification.In addition,in emerging fields such as nano-technology and bio-engineering of the continuing need to have different physical and chemical properties of new materials.Organic-inorganic hybrid materials combining the properties of the inorganic and organic species at the molecular level,which provide a possibility,to change the composition and structure of the materials by chemical methods at the same time.It is one of the subjects of concern for chemists and materials scientists and has many potential applications as important multifunctional materials.Our group researched in liquid-liquid system,extraction chemistry,and inorganic chemical materials for a long time and has accumulated a rich of experience in the solution structure of liquid-liquid system,solution structure and interphases transfer,as well as the preparation of functional materials.On the basis of previous work of our group,this thesis try to find a new liquid synthetic system to control synthesize of a special morphology of inorganic nano-materials and provides a new way to the preparation,assembly, modification of nano-materials;In addition,we had prepared a novel organicinorganic hybrid materials through ion exchange reaction that insert organic ligands in the layered inorganic materials and combining the magnetism of the inorganic part with the physical properties of inserted molecules,such as chiralitv and/or luminescence properties,which provide a experimental and theoretical basis for the liquid-phase synthesis of functional materials,the development of the inorganic materials and organic materials complementary functions,the design and synthesis of a specific composition,structure and functions of the new Organic-inorganic hybrid materials.The main results summarized are list as follows.1.Synthesis,Characterization and mechanism research of inorganic nano-materials（a）Single-crystalβ-MnO₂ nanotubes with diameters in the range 200-500 nm and lengths up to several micrometers were successfully prepared by a simple hydrothermal method through oxidizing MnSO₄ with NaClO₃ in the presence of poly（vinyl pyrrolidone）（PVP）.Based on a series of experimental analysis and discussions,the formation mechanism of these nanostructures was discussed briefly and found that the formation process ofβ-MnO₂ nanotubes follow a nucleation-dissolution-anisotropic growth-recrystallization mechanism.The present study has enlarged the family of nanotubes available, and offers a possible new,general route to one-dimensional single-crystalline nanotubes of other materials.（b）A convenient hydrothermal processing followed by a post-heat treatment route is proposed to synthesize well-dispersed branchedβ-MnO₂ multipods from branchedγ-MnOOH precursor.The key steps in our approach are as follows:By controlling the reactants concentration and reaction time,the monoclinic phase of MnOOH with novel branched multipods nanostructures was synthesized via the hydrothermal reaction of MnSO₄·H₂O and NaClO₃ at 160℃for 200 minutes;Then,the as-prepared branchedγ-MnOOH multipods were heated in air atmosphere at 400℃for 2 h,the branchedβ-MnO₂ nanostructures could be successfully obtained and without changing the precursory morphologies.These new structures presented here enrich the nanoscale community with new basic materials and offers a new approach for increasing structural complexity and enabling greater potential applications. Furthermore.the briefly discuss about their formation mechanisms provide insight into the formation processing of other transition metal oxide multipods （c）γ-manganese dioxides with novel saucer-shaped hexagonal nanoplatelets structure have been successfully synthesized via a simple chemical route using manganese nitrate as the manganese source and sodium chlorate as oxidant reagent without the addition of any surfactants or organic templates.The hexgonal nanoplatelets have edge lengths about of 250 nm with the thickness only several tens of nanometers and characterized using a variety of technical measurement methods.A possible formation mechanism of this novel morphology of nanoplates was proposed by tracking the crystallization and morphology of the products at different reaction stages.The magnetic properties of the products were investigated by a Quantum Design SQUID （superconducting quantum interference device）magnetometer and exhibit a paramagnetic behavior.The present study has offers a possible new,simple route for bulk synthesis of two-dimensionalγ-MnO₂ nanoplatelets and enlarged the family of MnO₂ available.2.The Preparation and Characterization of Organic-Inorganic Hybrid Materials.（a）Layered hydroxide metal acetates Co₂（OH）₃（CH₃COO）·H₂O with an interlayer spacing of 12.82（?）has been synthesized conveniently and rapidly as aggregates of thin crumpled sheets by a new method main routes conducted in ethanol-aqueous mixed solvents media.From the elemental analysis,in combination with the results obtained from thermal gravimetric measurements, the stoichiometry of the product was found to be Co₂（OH）_3.3 （CH₃COO）_0.7·2H₂O.The anhydrous form also can be easily obtained by moderate heating at 120℃only for one hour.The layered hydroxide cobalt acetates showing very interesting magnetic properties and its applications in the fields of anionic exchange reactions as good candidates made such an effective and facile approach very exciting for the preparation of hybrid organic-inorganic compounds.（b）We report the preparation,structure and physical properties of a series of multilayer multifunctional materials transition metal（Ⅱ）hydroxycitronellicates. These are prepared by anion-exchange reactions,starting from transition metal hydroxy-acetate layers M（Ⅱ）₂（OH）₃（OAc）·H₂O（M=Cu,Co）. The acetate ion is substituted for citronellic acid,which was one of several chiral 2- or 3-methyl branched acids.Similar exchange reactions are carried out with recemic,R and S chiral 2- or 3-methyl branched citronellic acids.The compounds,of general formulation M₂（OH）_（4-x）(C₁₀H₁₇O₂)X·zH₂O,exhibit a layered structure with a step-like variation of the basal spacing,according to inorganic metal hydroxy-acetate parity.Powder X-ray diffraction,IR spectroscopy,scanning electron microscope,as well as magnetic measurements etc.variety of techniques have been used in the characterization of the as-prepared samples.This study provides new insight on the multifunctional materials based on the grafting of optically active chiral organic ligants into inorganic magnetic layers.更多还原