【作者】 董丽红；

【导师】 褚莹；

【作者基本信息】 东北师范大学 ， 物理化学， 2009， 博士

【摘要】 纳米结构的可控合成是纳米科技发展的重要组成部分,是探索纳米材料性能和应用的基础。在纳米材料的化学制备方法中,液相法,尤其是以水为溶剂的液相法因低耗、环保而备受关注。本论文以胶体与界面化学基本原理为基础,利用两亲分子在纳/微米结构材料的合成与组装过程中的巧妙调控作用,制备了一系列低维的半导体纳米材料及其自组装超结构;探讨了两亲分子在半导体纳米材料形貌调控方面的作用机理;对所合成材料的组成、结构及形貌进行了细致的表征;考察了所制备的纳米材料的光学性质和光催化性能。利用两亲分子在水溶液中可以形成胶束的特性,以二硫化碳为硫源,在较低温度下（40或50℃）,采用不同的两亲分子（PVP或SDBS）分别得到了ZnS纳米空心球和纳米管。所制备的ZnS纳米空心球表现出良好的紫外光催化性能。利用两亲分子CTAB可以形成微乳液的特性,以溶剂热法制备了高轴径比的ZnS纳米线,通过改变实验参数获得了纳米棒和竹叶状纳米棒形貌的ZnS。其中竹叶状的纳米棒在电子束辐照下会变成空心结构。利用双齿配体乙二胺能够在晶体表面吸附的特性,在水溶液中加入适量乙二胺,通过水热路线制备了毛线球状的六方晶相的ZnS纳米线自组装结构。由于乙二胺较强的配位能力,本方法还可以用来制备多种离子（Eu、Cd、Mn、Co）掺杂的ZnS纳米结构,掺杂后产物的形貌仍旧保持了毛线球状的自组装结构,产物的发光性能因掺杂Eu离子而有很大增强和改变。由于蓬松的ZnS自组装纳米结构具有较大的比表面积,在紫外光催化方面表现出了优异的性能,部分掺杂产物还表现出优良的可见光催化性能。利用两亲分子CTAB在不同晶面具有选择性吸附的性能,以水为反应介质,分别在常规条件和水热条件下制备了松针、带、棒、毛绒花等多种形貌的PbS纳米结构以及Ag₂S纳米多面体和立方体。利用两亲分子PVP对不同晶面具有选择性吸附的性能,通过在水溶剂中引入生物相容性的甘油共同作溶剂,在室温条件下制备了PbS纳米直角立方体,产量大,重现性好,而且可以在存放了两年之久仍保持良好的形貌和单分散性。在所得到的PbS纳米立方体表面包覆一层SiO₂,可以拓宽其应用范围,而将核壳结构中的核溶解后得到了立方形的SiO₂纳米盒。利用层状结构晶体自身强烈的生长成一维结构的特性,通过适当调控反应条件,以水为反应介质,在室温条件下制备了花状的Bi₂S₃纳米自组装结构,在水热条件下得到了Ni（OH）₂纳米带、纳米线和纳米片,煅烧后得到了多孔的NiO纳米带、纳米线和纳米片。利用两亲分子PVP对ZnO的（0001）面的优势吸附特性,通过调节PVP的用量分别制备了由尖头纳米棒或平头纳米棒自组装而成的ZnO菊花状纳米结构。利用本体系还制备了Pb、Cu、Co掺杂的ZnO纳米自组装结构,并发现掺杂离子的种类对ZnO的形貌和自组装形式都有一定的影响,尤其是Co离子会减少自组装建筑单元的数目,在高浓度Co存在时得到的是具有三、四或者六臂的ZnO纳米自组装结构。光致发光测试表明掺杂态的ZnO纳米产物发光强度均高于未掺杂的ZnO纳米结构。通过本论文的研究,在基于胶体化学方法调控半导体纳米材料的形貌方面,获得了以下具有重要理论和实际意义的认识:（1）两亲分子对纳米材料制备的形貌调控作用是不容置疑的,往往通过形成胶束或是对不同晶面的选择性吸附来实现其形貌调控作用,另外还有利于防止纳米粒子的团聚。但两亲分子的作用并不是孤立实现的,制备体系的其他参数的协同作用不能忽视。（2）当物质本身具有强烈的生长成一维结构的趋势时,两亲分子的形貌调控作用便不明显,而具有这种强烈的一维生长结构趋势的物质往往具有层状结构,加入体系中的两亲分子容易插入层中而不是吸附在晶体表面,因此其形貌调控作用被减弱。另外,如果体系中存在着具有强配位能力的配体时,如乙二胺,它们与纳米晶表面的金属原子发生螯合从而吸附在纳米晶表面,起到了类似于两亲分子的作用,此时少量的两亲分子的引入也不能对产物形貌起到明显的调控作用。（3）通过控制适当的条件和设计适当的制备体系,在水相中实现各种纳米材料的多种形貌的制备是完全可能的。这就为工业批量生产奠定了良好的基础。更多还原

【Abstract】 The fabrication of nanoparticles is one of the important sections of nanoscience and nanotechnology, and also the base to investigate the distinctive properties and applications of nanostructures. Among all the synthesis methods to nanoparticles, liquid methods, especially the method using water as solvent, have attracted intensive interest because of their low cost and environmental benign characteristic. In this thesis, based on the colloid and interface science, a series of low dimensional semiconductor namomaterials and their self-assembly nanostructures have been synthesized by taking advantage of the morphology modulating effect of amphiphilic molecules. The modulating mechanism of the amphiphilic molecules has been discussed. The optical properties and the photocatalysis performance of the as-obtained products have also been investigated.By making use of the property that micelle can be form by amphiphilic molecules, carbon disulfide （CS₂） as sulfur source, at lower temperature （40 or 50 oC）, ZnS hollow nanospheres and nanotubes were synthesized by the assistance of different amphiphilic molecules PVP and SDBS, respectively. The as-prepared ZnS hollow nanospheres had good photocatalytic activity.By the microemulsion-mediated solvothermal method assisted by amphiphilic molecules CTAB, high-aspect-ratio ZnS nanowires were fabaricated. Moreover, ZnS nanorods and bamboo-leaf-like ZnS nanostructures were also obtained by modulating the reaction parameters. Especially, hollow bamboo-leaf-like ZnS nanostructures formed by radiating those bamboo leaves with electron beam during the TEM investigation.As a kind of polydentate ligand, ethylenediamine （en） can interact with the metal ions on the surface of nanocrystals, which make it like a kind of amphiphilic molecule. By introducing a certain amount of ethylenediamine into aqueous solution and adopting hydrothermal treatment, clewlike ZnS self-assembly nanostructure composed of ZnS nanowires were synthesized. Also, this method can produce not only pure ZnS nanostructures but also many kinds of ion doped ZnS nanostructures because of the strong anchor ability of ethylenediamine. And the morphology of the clewlike selfassembly nanostructure was maintained very well by the doped products. By the doping of Eu3+ ions, the photoluminescence emission intensity was much enlarged. For the large specific surface area, the as-obtained products possessed better photocatalysis property and some of them were visible-light responsive. Moreover, this kind of self-assembly nanostructure could be separated from the photocatlysis system easily by simple settlement.By taking advantage of the selective adsorption of amphiphilic molecule CTAB on different crystal faces and with water as reaction medium, PbS nanorods, nanobelts, nanovelvet-flowers, dendritic nanostructures and faceted and cubic Ag2S nanocrystals were fabricated.A novel water/glycerol/polyvinylpyrrolidone （PVP） ternary system was developed to realize the successful growth of PbS nanocubes with a narrow size distribution and sharp facets and edges using a one-step synthesis at room temperature for the first time. The synthesis was very fast, high yield, environment-friendly, and low cost. The product possessed uniform dimensionality, high crystallinity and better dispersibility. After dispersing the nanocubes in water or ethanol, the as-formed colloidal suspensions can maintain excellent stability for more than two year under ambient conditions. Uniform silica layers were successfully coated onto the nanocubes via a modified St?ber method to enhance their performance for promising applications. Moreover, by soaking the as-prepared PbS/SiO₂ core–shell nanocubes in hydrochloric acid aqueous solution, well-resolved cubic SiO₂ nanoboxes were obtained.By making use of the strong tendency toward 1D growth of crystal with lamellar intrinsic crystal structure and modulating the reaction conditions properly, with water as the reaction medium, Bi₂S₃ nanorods bundles as well as three-dimensional flower-like nanostructures were synthesized at room temperature, andα-Ni（OH）₂ nanobelts, nanowires, short nanowires, andβ-Ni（OH）₂ nanoplates were successfully prepared in high yields and purities by a convenient hydrothermal method under mild conditions from very simple systems composed only of NaOH, NiSO₄, and water. Furthermore, porous NiO nanobelts, nanowires, and nanoplates could also be obtained by annealing the as-prepared Ni（OH）₂ products.Under the assistance of amphiphilic molecule PVP, flower-like ZnO nanostructures self-assembled by nanorods were fabricated by hydrothermal route. The tip of the nanorods was cuspidal or flat depending on the amount of PVP as used. Pb, Cu, Co doped ZnO flower-like nanostructures self-assembled by nanorods were also prepared by this method. And all the dopants had influence on the morphology and the self-assembly style of the products in various degrees, in which the existence of Co ions resulted in the decreasing of the nanorods number in the self-assembly nanostructures, and three, four or six arms of ZnO nanostructures formed when the Co concentration was higher.Based on the research in this thesis, several conclusions are drawn in the following:（1） It is no doubt that amphiphilic molecules play important roles in the morphology control during the synthesis of nanomaterials, which is usually realized by the formation of micelles or selective absorption on different crystal faces. Moreover, the adsorption of amphiphilic molecules is helpful to prevent the aggregation of the nanoparticals. But the effect of amphiphilic molecules dose not take place independently, the other parameters of the synthesis system can not be neglected. （2） When the crystals have strong tendency toward 1D growth, the morphology control effect of amphiphilic molecules is not obvious. The reason for that is crystals with strong tendency toward 1D growth usually possess lamellar intrinsic crystal structure, the amphiphilic molecules tend to insert into the interbedded space but adsorb on the surface of the crystals, as a result, the morphology control effect of amphiphilic molecules was weakened. Moreover, when ligands with strong coordination ability exist in the synthesis system, such as ethylenediamine, they interact with the metal ions on the surface of nanocrystals, which make it like a kind of amphiphilic molecule, so the addition of a small amount of amphiphilic molecules can not make obvious morphology control effect.（3） By controlling suitable conditions and designing proper synthesis systems, it is possible to realize the fabrication of nanomaterials with various morphologies in aqueous medium, which lays better foundation for industry batch production.更多还原