碳纳米管和碳微米管的结构、性质及其应用

【关键词】:电化学;;碳纳米管;;碳微米管;;石墨烯;;量子导线;;锂离子电池;;超级电容器;;储氢材料;;化学修饰
【摘要】:评述碳纳米管和碳微米管的结构、性质及其应用,指出碳纳米管可看作是石墨烯片按照一定的角度卷曲而成的纳米级无缝管状物,根据层数不同可分为多壁碳纳米管和单壁碳纳米管.由于碳纳米管管壁中的碳原子采用的是sp2杂化,因此碳纳米管沿轴向具有高模量和高强度,可用于增强复合材料的力学性能;而碳纳米管圆筒状弯曲会导致量子限域和σ-π再杂化,这种再杂化结构特点以及π电子离域结构赋予了碳纳米管特异的光、电、磁、热、化学和力学性质;碳纳米管的管腔内部是纳米级中空结构,可作为纳米级分子反应器和存储容器.但碳纳米管的管径尺寸太小、表面缺陷多、团聚严重等问题一直影响着碳纳米管在实际中的应用.而碳微米管的出现弥补了其不足,碳微米管具有与碳纳米管相似的管状结构,在保持纳米级管壁厚度的同时,能拥有微米级的管径,巨大的管壁外表面,相当于一张微米级的石墨烯网状膜,因此碳微米管能同时拥有碳纳米管和石墨烯的独特物理和化学性能.通过对碳微米管各项性能的研究表明,碳微米管的管壁具有规整的石墨烯结构,管腔具有微米级中空管结构,有较高的比表面积,电学和化学性能良好.利用其优良的电学性能,它们能较好地应用在量子导线和晶体管阵列;同时利用其优良的化学和电化学性能,也能广泛用于锂离子电池、超级电容器和储氢材料.
The carbon nanotube(CNTs) can be considered equivalent to a graphene sheet rolled into a seamless tube capped on both ends.CNTs can be divided into multi-walled carbon canotubes(MWNTs) and single-walled carbon nanotubes(SWNTs) according to the number of graphene layers.CNTs have high modulus and tensile along the axial because the tube wall of CNTs is composed of the sp2 hybridized orbitals hexagonal carbon atoms network,which can be used to reinforce the mechanical properties of the composite material.The cylindrical structure of CNTs will cause the quantum confinement and σ-π rehybridization.This structural feature of the rehybridization and electron confinement can give carbon nanotubes unique optical,electronic,magnetic,thermal,chemical and mechanical properties.CNTs with the hollow tubular structure also can be used as a reactor and storage container.However,problems arise from the small size of the pipe diameter;surface deficiency and serious agglomeration badly restrict the development of CNTs.The appearance of CMTs makes up for the shortages of CNTs.CMTs have the same tubular structure as CNTs.CMTs have a micro-scale pipe diameter and a large outside surface for a tube wall while maintaining a nano-scale tube wall thickness,which is equivalent to a micro-scale graphene membrane.So,CMTs possess the unique physical and chemical properties of both the CNTs and graphene.A comprehensive study of the performance of the CMTs shows that the tube wall of the CMTs has a well-defined structure of graphene,micro-scale hollow structure lumen,large specific surface area and favorable electrical and mechanical properties.With superior electrical properties,CMTs can be applied in quantum wires and transistor array.At the same time,because of their excellent chemical and electrochemical properties,they can also be applied in lithium-ion batteries,supercapacitors and hydrogen storage materials,etc.