共查询到19条相似文献,搜索用时 187 毫秒
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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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Jinlong Yang 《物理化学学报》2020,36(8):2002014-0
正结构决定性能,作为典型一维碳材料的单壁碳纳米管具有非常独特的光电性质,因而,单壁碳纳米管的结构控制制备一直是人们关注的热点问题,也成为该领域最具挑战的课题之一~(1,2)。目前,化学气相沉积方法是可控制备碳纳米管的主要方法,在化学气相沉积反应过程中,碳源在催化剂表面裂解成核,进而生长出结构不同、长度各异的单壁碳纳米管。为深入探索碳纳米管的生 相似文献
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针尖化学方法研究单壁碳纳米管末端羧基的解离性质 总被引:2,自引:0,他引:2
针尖化学利用化学手段对扫描探针显微镜 ( SPM)的针尖进行功能化修饰 ,将其作为化学反应的“探针”用于研究表面的局域化学反应性质、跟踪表面发生的化学反应过程等 [1] .用针尖化学技术来研究自组装膜 ( SAMs)表面酸碱基团的局域解离性质 ,称之为化学力滴定 [2~ 8] .利用表面缩合方法将单壁碳纳米管短管组装到 AFM针尖上 ,通过测定针尖上碳纳米管的末端基团与羟基自组装膜表面之间的粘滞力 ,研究碳纳米管末端羧基的解离性质 ,可得到碳纳米管结构与化学性质的信息 .1 实验部分1 .1 碳纳米管针尖和羟基末端自组装膜的制备 基底 [Si( … 相似文献
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高温煅烧Mo改性的Fe/MgO催化剂用于制备管径分布均一的单壁碳纳米管 总被引:1,自引:0,他引:1
研究了在以甲烷化学气相沉积法制备单壁碳纳米管的过程中高温煅烧预处理(900℃煅烧10h)对Mo改性Fe/MgO催化剂的作用.发现这种预处理有利于Fe在催化剂中的稳定和分散,从而制备出管径均一的单壁碳纳米管.采用能谱元素分析、高分辨透射电镜、X射线衍射、比表面积测量、拉曼光谱和热重分析对样品进行了表征.结果表明,在碳纳米管生长的过程中,铁元素在催化剂表面富集,单壁碳纳米管生长于富集铁的纳米颗粒上,并存在碳管直径与铁颗粒尺寸的依赖关系.Mo存在时可煅烧形成FeMoO4复合氧化物,后者比MgFe2O4相更加稳定.Mo/Fe比例对提高单壁碳纳米管的生长密度、纯度与管径均一性等均有明显影响.上述研究对进一步精确控制制备单壁碳纳米管有重要意义. 相似文献
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设计合成可作为碳纳米管片段的共轭芳烃大环近年来吸引了化学家们广泛的研究兴趣,人们希望从这些共轭芳烃大环出发,通过利用“自下而上”的策略合成单壁碳纳米管。需要指出的是,传统制备碳纳米管的方法,如电弧法、化学气相沉积法等,都很难形成均一的单壁碳纳米管。而这种“自下而上”的策略为高效合成尺寸均一的单壁碳纳米管提供了可行的方法,这种合成方法因此成为了当下合成单壁碳纳米管的热点,但也仍是一大挑战。本文从二维碳纳米环、碳纳米带和三维碳纳米笼三个方面概述关于这类共轭芳烃大环研究的新进展,着重介绍了共轭碳纳米环的设计原则和合成方法,并突出介绍了多环芳烃碳纳米环。多环芳烃通常具有优良的光电性质,以其为基元构筑的共轭碳纳米结构不仅可以作为碳纳米管的合成前体,而且其自身也会表现出新的光电性质。 相似文献
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碳纳米管基气体传感器研究进展 总被引:1,自引:0,他引:1
碳纳米管具有灵敏度高、响应快和工作温度低等优异的气敏特性,近年来碳纳米管基气体传感器的研究成为研究热点.概述了碳纳米管基气体传感器的种类、结构特点、气敏性能和未来的发展方向,着重介绍了纯的碳纳米管包括单壁碳纳米管、多壁碳纳米管和碳纳米管阵列的气敏特性,以及碳纳米管的修饰或碳纳米管与高分子材料、氧化物等复合对其气敏性能的影响. 相似文献
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不同结构碳纳米管的电磁波吸收性能研究 总被引:14,自引:0,他引:14
研究了单壁、多壁碳纳米管(聚团状、阵列状)以及未纯化与纯化后碳纳米管在2~18 GHz范围内的电磁波吸收性能. 通过测定不同结构碳纳米管粉体的介电常数以及磁导率, 得到损耗因子及衰减常数大小顺序为: 阵列状多壁碳纳米管>原生聚团状多壁碳纳米管>纯化聚团状多壁碳纳米管>原生单壁碳纳米管>纯化后单壁碳纳米管. 相比多壁碳纳米管, 单壁碳纳米管衰减常数随频率变化较小, 且具有较宽的吸收峰. 模拟计算和实验测试结果都表明, 碳纳米管/聚合物复合材料具有优良的电磁吸波性能. 相似文献
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Single-walled carbon nanotubes (SWNTs) possess unique electronic properties that make them very promising materials for use in both nano-electronics and thin film devices. However, SWNTs are always produced as a mixture of metallic and semiconducting nanotubes, which is a major roadblock to their widespread application. This tutorial review provides a brief summary of ways of separating single-walled carbon nanotubes into metallic and semiconducting fractions. Various methods including selective growth, selective removal, selective adsorption and band structure modulation--all of which aim to produce pure SWNTs with well-defined electronic properties--are systematically discussed. The main problems in this field, the outlook for separation techniques and some views of future developments are presented. 相似文献
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Li X Tu X Zaric S Welsher K Seo WS Zhao W Dai H 《Journal of the American Chemical Society》2007,129(51):15770-15771
Single-walled carbon nanotubes (SWNTs) are potential materials for future nanoelectronics. Since the electronic and optical properties of SWNTs strongly depend on tube diameter and chirality, obtaining SWNTs with narrow (n,m) chirality distribution by selective growth or chemical separation has been an active area of research. Here, we demonstrate that a new, bimetallic FeRu catalyst affords SWNT growth with narrow diameter and chirality distribution in methane CVD. At 600 degrees C, methane CVD on FeRu catalyst produced predominantly (6,5) SWNTs according to UV-vis-NIR absorption and photoluminescence excitation/emission (PLE) spectroscopic characterization. At 850 degrees C, the dominant semiconducting species produced are (8,4), (7,6), and (7,5) SWNTs, with much narrower distributions in diameter and chirality than materials grown by other catalysts. Further, we show that narrow diameter/chirality growth combined with chemical separation by ion exchange chromatography (IEC) greatly facilitates achieving single (m,n) SWNT samples, as demonstrated by obtaining highly enriched (8,4) SWNTs with near elimination of metallic SWNTs existing in the as-grown material. 相似文献
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Star A Joshi V Skarupo S Thomas D Gabriel JC 《The journal of physical chemistry. B》2006,110(42):21014-21020
Here we demonstrate design, fabrication, and testing of electronic sensor array based on single-walled carbon nanotubes (SWNTs). Multiple sensor elements consisting of isolated networks of SWNTs were integrated into Si chips by chemical vapor deposition (CVD) and photolithography processes. For chemical selectivity, SWNTs were decorated with metal nanoparticles. The differences in catalytic activity of 18 catalytic metals for detection of H(2), CH(4), CO, and H(2)S gases were observed. Furthermore, a sensor array was fabricated by site-selective electroplating of Pd, Pt, Rh, and Au metals on isolated SWNT networks located on a single chip. The resulting electronic sensor array, which was comprised of several functional SWNT network sensors, was exposed to a randomized series of toxic/combustible gases. Electronic responses of all sensor elements were recorded and the sensor array data was analyzed using pattern-recognition analysis tools. Applications of these small-size, low-power, electronic sensor arrays are in the detection and identification of toxic/combustible gases for personal safety and air pollution monitoring. 相似文献
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Bo‐Cheng Wang Houng‐Wei Wang I‐Chun Lin Yun‐Shan Lin Yu‐Ma Chou Houn‐Lin Chiu 《中国化学会会志》2003,50(5):939-945
A semiempirical PM3 quantum computational method has been used to generate the electronic and optimized geometrical structure of SWNT of zigzag and armchair types. We shed light on the electronic structures of SWNT with various diameters and lengths of the tube. Particularly, the calculated HOMO, LUMO and band‐gap of SWNT are not monotonic but exhibit a well‐defined oscillation, which depends on the tubular diameter and the tubular length. Calculated HOMO, LUMO and band‐gap of the zigzag SWNTs have oscillated with tubular diameter as they contain an odd or even number of benzenoids in the circular plane of the carbon nanotube. The zigzag SWNTs with an odd number of benzenoids have a higher band‐gap than those of SWNTs with an even number of benzenoids in the circular plane of the carbon nanotube. Calculated results also reveal that the tubular length in the zigzag SWNTs influences the band‐gaps very little. For the armchair SWNT, calculated HOMO, LUMO and band‐gap contained the oscillate depending on the number of carbon sections in the tubular length axis. Their repeat sections are 3n‐1, 3n and 3n+1. The armchair SWNT with 3n+1 sections has a high band‐gap while the SWNTs with 3n‐1 sections have a low band‐gap. The tubular diameters of armchair SWNT influence the HOMO, LUMO and band gap very little. 相似文献
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Cigang Xu Emmanuel Flahaut Sam R. Bailey Gareth Brown Jeremy Sloan Karl S. Coleman V. Clifford Williams Malcolm L. H. Green * . Inorganic Chemistry Laboratory University of Oxford Oxford OX QR UK 《高等学校化学研究》2002,18(2):130-132
IntroductionSingle walledcarbonnanotubes(SWNTs)havebeensynthesisedbyusingvariousmethods[1— 3] andthechemicalvapourdeposition (CVD )methodhasbeenconsideredasa promisingmethodto produceSWNTsonanindustrialscale[3— 5] .However ,alltheSWNT productssynthesisedtodateco… 相似文献
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Possible ways for manipulating carbon nanotubes (CNTs) with cyclic supermolecules are studied using density functional theory. Electronic structure calculations with structure optimizations have been performed for the (4,4) and (8,0) single-walled carbon nanotubes (SWNTs) complexed with crown ethers as well as for the (4,0) SWNT with beta-cyclodextrin. A slight polarization of charge in both the nanotube and the supermolecule is observed upon rotaxane complexation, but the interaction is mainly repulsive, and the systems stay 2.8-3.5 A apart. The supermolecule does not affect the electronic band structure of the nanotube significantly within such a configuration. The situation differs noticeably for chemically cross-linked SWNTs and crown ethers, where a peak arises at the Fermi energy in the density of states. As a result, the band gap of semiconducting CNT(8,0) (0.5 eV) vanishes, and a new conduction channel opens for the metallic CNT(4,4). 相似文献
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Preferential growth of single-walled carbon nanotubes on silica spheres by chemical vapor deposition
Zhou W Zhang Y Li X Yuan S Jin Z Xu J Li Y 《The journal of physical chemistry. B》2005,109(15):6963-6967
The preferential growth of single-walled carbon nanotubes (SWNTs) on silica spheres with various diameters was realized for the first time by chemical vapor deposition (CVD) of methane. SWNTs tend to wrap the silica spheres to form a new superstructure of uniform SWNT nanoclaws when the diameters of the silica spheres are larger than 400 nm. The SWNTs obtained on silica spheres have highly graphitic tubular walls as characterized by Raman spectroscopy and HRTEM. This is a new method to obtain tunable uniform elastic deformation of SWNTs, which may act as the model for the study about the effect of delocalized bending on the properties of SWNTs. In addition, the combination of SWNTs with monodispersed silica spheres could conveniently integrate SWNTs into photonic crystals. 相似文献