【作者】 王治宇；

【导师】 邱介山； 赵宗彬；

【作者基本信息】 大连理工大学 ， 化学工艺， 2007， 博士

【摘要】 以碳纳米管为代表的一维纳米材料是目前研究最为广泛的一类新型功能材料，其可控合成是当今纳米材料研究领域的前沿和热点之一。如何设计结构新颖、形貌独特的一维纳米材料，并在制备过程中实现对其结构维度、物质组成的准确控制，进而对其本征性能进行调变对于深入理解物质结构与性质的关联、人工设计合成新型功能材料具有重要意义。本文就碳纳米管及由其衍生的一维碳-金属（或其化合物）复合纳米材料的结构选择制备进行了系统研究，主要研究结果如下：以煤为碳源前躯体，在电弧等离子体条件下实现了碳纳米管的结构选择制备。通过调节反应条件如催化剂种类、缓冲气氛种类及压力等可以得到形态结构各异的碳纳米管如双壁碳纳米管、多壁碳纳米管、分枝碳纳米管等。在惰性气氛中，以活性较高的铁作为催化剂时可以制备双壁碳纳米管，其管径分布在1-5 nm左右，管壁间距恒定（约0.41nm），在范德华力作用下可以定向集结形成长达20 cm的宏观绳状沉积物；而以传统意义上对碳材料生长催化活性极弱的铜作为催化剂时则可实现多壁碳纳米管及分枝碳纳米管的大量合成，其中分枝碳纳米管的纯度经优化后可达90％以上。以碳纳米管作为形态模板，通过电弧等离子体原位填充技术制备了外壳为碳纳米管、内芯为一维铜或稀土氟化物纳米线的“纳米电缆”复合结构（Cu／LnF₃@CNT纳米电缆）。在碳纳米管内腔中合成了长达十余微米、直径分布均一的超长铜、稀土氟化物晶体纳米线并对其在碳纳米管限域内腔中的晶体生长行为进行了探讨；研究表明：碳纳米管的紧密包覆可以严格限制物质晶体的外延生长，从而强制其以理想各向异性方式生长形成长程结构连续的一维纳米线，在此过程中，晶体纳米线可以沿高能晶面或低能晶面方向取向，生长模式较为多样。在纳米电缆结构制备的基础上，通过热氧化反应除去碳纳米管壳层，可以在不损伤晶体纳米线形态及结构的前提下实现由稀土氟化物@碳纳米管复合结构向纯净稀土氟化物纳米线的转化。利用水热法，在温和条件下原位制备了Cu@C纳米电缆复合结构。此类纳米电缆结构的外壳为厚度均一（20-30 nm）的无定形炭层，内芯为直径100-200 nm、长约数微米的铜晶体纳米线；经高温炭化处理后，Cu@C纳米电缆可部分向Cu@CNT纳米电缆结构转化。通过调节反应条件，使用类似的液相方法还可以实现炭微米球或氧化铜微米球的制备。更多还原

【Abstract】 As a class of novel functional materials, one-dimensional(1D)nanomaterials have attractedextensive research interests across the world in recent years, of which the controllablesynthesis is one of the hot topics of nanoscience and nanotechnology. The big challenge onthe understanding of the relationship between the structure and characteristics of the 1Dnanomaterials and their artificial synthesis is how to design them with novel structure andunique shape, and how to precisely control the structure, dimensionality and composition ofthe materials, further to tailor their intrinsic properties. In the present thesis, the research isprimarily focused on the structure-selective synthesis and characterization of carbonnanotubes (CNTs) and related 1D hybrid nanostruetures, of which the majority results arebriefly summarized as follows.The CNTs with diverse morphologies have been selectively synthesized from coal via arcdischarge method by tuning the reaction parameters such as the catalysts, carbon source andbuffer gas to be appropriate. High-quality double-walled CNTs (DWNTs) could besynthesized in large scale by the arc-discharge of coal-based carbon with Fe as catalyst in ahydrogen-free atmosphere, of which the diameter falls in a range of 1-5 nm and the distancebetween the tube walls is about 0.41 nm. When the Cu, a traditional weak catalyst for carbonmaterial growth, was used, abundant multi-walled CNTs (MWNTs) could be produced, andtheir structure could be deformed through the Cu-catalyzed introduction of non-hexagonalcarbon ring into the lattice of the tubes. Consequently, branched CNTs (BCNTs) wereobtained after the optimization of the reaction, of which the purity can be as high as about90％.The CNTs synthesized above could be used as ideal nanotemplate for the synthesis ofM@CNT(M: copper or lanthanide fluoride) nanocables by an in-situ filling technique.Super-long crystalline nanowires(over ten micrometers in length) of copper or lanthanidefluoride could be fabricated inside the inner cavities of the CNTs under proper conditions.The crystal nature of lanthanide fluoride nanowires confined inside the CNT cavity wasinvestigated to make the confining effect of the nanotubes clear. It indicates that the presenceof CNT sheath retards the lateral growth of filling crystals by preventing the formation of freesurface, and enforces the formation of 1D nanowire with diverse growth directions inside thetube, whereas for uncoated nanowires the surface energy and facet formation plays crucial role for their intrinsic anisotropic growth. This work can be extended to the preparation ofpure lanthanide fluoride nanowires from the corresponding nanoeables by simple thermaloxidation treatment while their 1D shape and crystalline nature remaining unchanged.In addition, Cu@C nanoeables have been produced by a mild solution technique, in whichthe carbon coating is amorphous while the copper nanowires are well crystalline. After thecarbonization, the carbon coating outside the copper nanowires could be evolved to be ananalogy of graphitie structure. Furthermore, the technique can be also used for the synthesisof the microspheres of carbon or CuO after the modification of reaction conditions.更多还原