Synthesis And Characterization Of One-dimensional Carbon Nanomaterials And Related Hybrid Structures

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 about90ï¼….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.