共查询到18条相似文献,搜索用时 107 毫秒
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《中国科学:化学》2015,(10)
水平阵列状碳纳米管是指利用化学气相沉积法在平整基底上制备的沿基底形貌或气流定向、平行排列、能够达到毫米级甚至厘米级以上长度的碳纳米管类型.水平阵列碳纳米管遵循自由生长的模式,缺陷很少,能够体现出碳纳米管本征的优异性能,是透明显示、微电子、超强纤维以及航空航天等领域的尖端基础材料.本文总结了水平阵列碳纳米管近年来的相关进展,并对其生长机理、结构可控制备、光学可视化技术、可控操纵技术、力学、电学及热学方面的优异性能,以及管壁间的超润滑现象等方面的进展进行了评述.目前,水平阵列碳纳米管可以达到半米以上的长度,并且具有完美的结构和优异性能,从而使其具有广阔的应用前景.同时,本文也对碳纳米管水平阵列密度过低的机理进行了分析,并对实现其批量制备的方法和未来发展进行了展望. 相似文献
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采用无模板的化学气相沉积(chemical vapour deposition,CVD)法,以二甲苯和乙二胺为反应物,二茂铁为催化剂,以石英玻璃为衬底,制备了大面积、垂直于石英衬底生长、掺杂N的定向碳纳米管阵列。扫描电镜检测表明制备的定向碳纳米管阵列具有很好的定向性,而且管身平直。高分辨透射电镜的检测表明制备的碳纳米管具有较好的石墨化程度和较高的纯度,首次在碳纳米管内腔中发现了原位生长的“类富勒烯”结构。拉曼光谱的检测表明制备的定向碳纳米管阵列中含有大量的单壁碳纳米管。X射线光电子能谱检测表明N原子成功地被掺进了碳纳米管中,而且N原子的百分比随着碳源中N原子浓度的增加而增加,当碳源中nC∶nN比为1∶1的时候,在掺杂的碳纳米管中N原子的物质的量分数可以达到2.51%。 相似文献
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催化剂对纳米聚团床法制备的纳米碳材料形貌的影响 总被引:3,自引:0,他引:3
在纳米聚团床中用催化化学气相沉积法批量制备了碳纳米管,研\r\n究了过渡金属催化剂对碳纳米管形貌和产量的影响.实验结果表明,含\r\n铁催化剂的活性较低,产率较低,但产品质量较好;含镍催化剂的活性\r\n较高,产率较高,但产品质量较差;在钴催化剂作用下发现了一种新型\r\n的针状纳米碳材料.用含载体较少的铁催化剂可以得到纯度较高且微观\r\n结构较好的碳纳米管,但产率较低;不含任何载体的纯镍催化剂则不能\r\n得到碳纳米管.适宜的催化剂组成、催化剂活性点的均匀分布和裂解速\r\n度的控制等构成了纳米聚团床大批量制备碳纳米管技术的关键. 相似文献
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单壁碳纳米管在原子尺度的结构变化即可导致其电学、光学方面等性质的多样性和非连续的变化——如电学性质上可呈现半导体性或金属性。然而,在单壁碳纳米管表现出诸多优异性能的同时,如何实现碳纳米管的结构控制制备仍面临严峻的挑战。本文以单壁碳纳米管的管径、导电属性和手性控制为目标,介绍单壁碳纳米管的结构控制生长方法,主要包括温度扰动法、金属催化剂结构设计法、生长气氛调控法、外场辅助法、基底诱导法、非金属粒子催化法和sp2碳结构模板法等。并在此基础上总结了单壁碳纳米管结构控制生长的基本思路及实现途径,以期为后续单壁碳纳米管的规模化应用奠定基础。 相似文献
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碳纳米管具有优秀的导电性能、 透光性能和十分突出的柔性, 在柔性透明导电薄膜中有着良好的应用前景. 如何制备同时拥有良好导电性能和透光性能的碳纳米管薄膜是这一领域研究的核心问题. 本综述介绍了碳纳米管薄膜的制备方法, 并重点讨论了基于漂浮催化剂化学气相沉积法的碳纳米管薄膜的可控制备. 在生长过程中限制碳纳米管的团聚、 增加碳纳米管的长度、 降低杂质的含量是提高碳纳米管薄膜性能的主要策略. 相似文献
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Reginald B. Little 《Journal of Cluster Science》2003,14(2):135-185
The discovery, synthesis, characterization, and applicability of carbon nanotubes have produced tremendous excitement and interest among scientists and engineers. In particular, the use of these unique tubular nanostructures for new strong lightweight materials, nanoelectronics, fuel storage and cells, electron emitters and bio, scanning probe microscopy, and chemical sensing devices has created an intense effort to advance the synthesis so as to mass produce carbon nanotubes with control over diameter and helicity. The massive and controlled synthesis of this heralded nanostructure has been a great challenge. Although significant progress has advanced the preparation, more synthetic development is required. The syntheses have so far involved three main approaches: arc discharge vaporization, laser vaporization, and catalytic chemical vapor deposition. The synthetic trend has progressed to a point where further advancement with these techniques will require a better understanding of the mechanism of nucleation and growth. The mechanics of carbon nanotube nucleation and growth involve very complex and diverse phenomena occurring under extreme conditions and on the mesoscopic scale. As yet the detail mechanism is unknown. Difficulties with experimental probing and computational simulation have increased the mystery of this mechanism. This review presents an account of research on the synthesis of carbon nanotubes and the mechanism of formation. This overview includes all three mentioned synthetic approaches and hybrids thereof. On the basis of this broad account a comprehensive mechanism for carbon nanotube nucleation and growth naturally arises. This mechanism is qualitative and it hopes to inspire more quantitative exploration and synthetic advancement. 相似文献
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Ji-cheng Zhang Yong-jian Tang Yong Yi Min-jie Zhou Kang-fu Ma Wei-dong Wu Chao-yang Wang Yan Zhao Bing-chi Luo Zhuo Wang 《化学物理学报(中文版)》2015,28(5):617-622
Vertically aligned multi-walled carbon nanotube arrays grown on quartz substrate are obtained by co-pyrolysis of xylene and ferrocene at 850 oC in a tube furnace. Raman spectroscopy and high resolution transmission electron microscopy measurements show that the single-walled carbon nanotubes are only present on top of vertically aligned multi-walled carbon nanotube arrays. It has been revealed that isolated single-walled carbon nanotubes are only present in those floating catalyst generated materials. It thus suggests that the single-walled carbon nanotubes here are also generated by floating catalyst. Vertically alignedcarbon nanotube arrays on the quartz substrate have shown good orientation and good graphitization. Meanwhile, to investigate the growth mechanism, two bi-layers carbon nan-otube films with di erent thickness have been synthesized and analyzed by Raman spectroscopy. The results show that the two-layer vertically aligned carbon nanotube films grow “bottom-up”. There are distinguished Raman scattering signals for the second layer itself, surface of the first layer, interface between the first and second layer, side wall and bottom surface. It indicates that the obtained carbon nanotubes follow the base-growth mechanism, and the single-walled carbon nanotubes grow from their base at the growth beginning when iron catalyst particles have small size. Those carbon nanotubes with few walls (typically <5 walls) have similar properties, which also agree with the base-growth mechanism. 相似文献
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Straight and helical carbon nanotubes with diameter from 20 to 60 nm have been synthesized through catalytic decomposition of polyethylene in autoclave at 700 °C. The X-ray power diffraction pattern indicates that the products are hexagonal graphite, and transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) images reveal the morphologies and structures of carbon nanotubes. The effects of reaction temperature, catalyst and maleated polypropylene on the growth of the carbon nanotubes were also discussed, and the growth mechanism of the CNTs was proposed. Pyrolysis of polyethylene is a promising green chemical method for economically producing carbon nanotubes. 相似文献
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In this work, a novel method for the fabrication of magnetic carbon nanotubes based on 'aggregation wrap' was proposed. When carbon nanotubes and magnetic nanoparticles were vortically mixed in a solvent, the magnetic nanoparticles were wrapped into the carbon nanotube bundles that formed during the aggregation process, leading to the formation of magnetic carbon nanotubes. Thus, the resultant material can be separated from the solvent rapidly and conveniently by a magnet. Our investigation demonstrated that the 'aggregation wrap' mechanism for the preparation of magnetic composite is also applicable to other self-aggregated micro/nanomaterials, including graphene, graphite, C(60), etc. To testify the feasibility of the magnetic composites in sample preparation, the resultant magnetic carbon nanotubes were applied as sorbents for magnetic solid-phase extraction (MSPE) of estrogens in milk samples. Under optimized conditions, a rapid, convenient and efficient method for the determination of estrogens in milk samples was established by the combination of MSPE with high-performance liquid chromatography with fluorescence detector. The linearity range of the proposed method was 5-2000 μg/L with correlation coefficients (R) of 0.9983-0.9994. The limit of detection (LOD) for three estrogens ranged from 1.21 to 2.35 μg/L. The intra- and inter-day relative standard deviations (RSDs) were <9.3%. The reproducibility of the MSPE with different batches of magnetic carbon nanotubes was acceptable with RSD values <3.6%. 相似文献