Large-Scale Synthesis of Aligned Carbon Nanotubes

Large-scale synthesis of aligned carbon nanotubes was achieved by using a method based on chemical vapor deposition catalyzed by iron nanoparticles embedded in mesoporous silica. Scanning electron microscope images show that the nanotubes are approximately perpendicular to the surface of the silica and form an aligned array of isolated tubes with spacings between the tubes of about 100 nanometers. The tubes are up to about 50 micrometers long and well graphitized. The growth direction of the nanotubes may be controlled by the pores from which the nanotubes grow.     

Crystalline Ropes of Metallic Carbon Nanotubes

Fullerene single-wall nanotubes (SWNTs) were produced in yields of more than 70 percent by condensation of a laser-vaporized carbon-nickel-cobalt mixture at 1200degreesC. X-ray diffraction and electron microscopy showed that these SWNTs are nearly uniform in diameter and that they self-organize into "ropes," which consist of 100 to 500 SWNTs in a two-dimensional triangular lattice with a lattice constant of 17 angstroms. The x-ray form factor is consistent with that of uniformly charged cylinders 13.8 +/- 0.2 angstroms in diameter. The ropes were metallic, with a single-rope resistivity of <10(-4) ohm-centimeters at 300 kelvin. The uniformity of SWNT diameter is attributed to the efficient annealing of an initial fullerene tubelet kept open by a few metal atoms; the optimum diameter is determined by competition between the strain energy of curvature of the graphene sheet and the dangling-bond energy of the open edge, where growth occurs. These factors strongly favor the metallic (10,10) tube with C5v symmetry and an open edge stabilized by triple bonds.     

Nanocapillarity and Chemistry in Carbon Nanotubes

Open carbon nanotubes were filled with molten silver nitrate by capillary forces. Only those tubes with inner diameters of 4 nanometers or more were filled, suggesting a capillarity size dependence as a result of the lowering of the nanotube-salt interface energy with increasing curvature of the nanotube walls. Nanotube cavities should also be less chemically reactive than graphite and may serve as nanosize test tubes. This property has been illustrated by monitoring the decomposition of silver nitrate within nanotubes in situ in an electron microscope, which produced chains of silver nanobeads separated by high-pressure gas pockets.     

碳纳米管改性的蜡基复合粘结剂

通过熔融共混将功能化的碳纳米管引入到蜡基粘结剂中,得到碳纳米管改性的复合粘结剂.扫描电镜（SEM）显微照片显示,功能化的碳纳米管能均匀分散在粘结剂基体中.偏光显微照片和热性能分析结果表明,碳纳米管的加入能有效地提高粘结剂的结晶度和热稳定性,进而改善生坯在脱脂时的保形性.碳纳米管与粘结剂的非共价键结合有助于碳纳米管的均匀分散,更可能有利于复合材料成型后的脱脂.     

Single-Electron Transport in Ropes of Carbon Nanotubes

The electrical properties of individual bundles, or "ropes," of single-walled carbon nanotubes have been measured. Below about 10 kelvin, the low-bias conductance was suppressed for voltages less than a few millivolts. In addition, dramatic peaks were observed in the conductance as a function of a gate voltage that modulated the number of electrons in the rope. These results are interpreted in terms of single-electron charging and resonant tunneling through the quantized energy levels of the nanotubes composing the rope.     

碳纳米管的表面修饰及其在水中的分散性能研究

采用硫酸和硝酸混合酸对催化裂解法(CⅧ法)制备的多壁碳纳米管(CNTs)进行纯化，然后运用十六烷基三甲基溴化胺(HTAB)对CNTs进行修饰，并利用透射电子显微镜、红外光谱和拉曼光谱表征了CNTs的表面结构；另外，通过数码照相机和乌氏粘度计研究了修饰的CNTs在水中的分散性能，实验结果表明，通过混合酸处理能够使CNTS表面拥有较多的羟基和羧基官能团；在氨水的作用下，CNTs能够被HTAB所包覆，而且修饰后的CNTs在水中的分散性能得到提高．     

碳纳米管在电子器件中的应用

碳纳米管作为一种新型碳材料具有独特的纳米结构和优异的力学、电学、热学和物理化学性能,在各个领域显示出诱人的潜在应用价值和前景,引起了科学界广泛的研究。从碳纳米管的结构人手,综述了碳纳米管的热力学性质、场发射特性、导电性以及基于碳纳米管的结（对应于硅基微电子学中的二极管）,场效应管（FET,对应于硅基微电子学中的FET）和单电子晶体管等三种电子器件的研究情况,并讨论了其在电子器件领域的应用。     

多壁碳纳米管侧壁的功能化与表征

利用丁二酸酰基过氧化物分解产生的羧酸自由基与多壁碳纳米管(MWCNTs)进行自由基加成反应,对其侧壁实现羧酸化,并依次对其进行酰氯化、胺化处理,获得侧壁酰胺化的MWCNTs.采用FT-IR,Raman以及UV-Vis光谱对其进行了表征.结果表明:碳管表面接枝上了羧酸基团,且数量较纯化后的碳管有较大幅度的增加,表征其结构缺陷的I(D 2D)/IG比值增加了0.2,同时酰胺化的MWCNTs紫外可见光谱在320 nm处出现了—CONH—键的π→π*跃迁的吸收峰.     

碳纳米管非均匀氢等离子体微波吸收的数值模拟

提出碳纳米管非均匀氢等离子体薄膜的层状介电模型,探讨等离子体密度分布对碳纳米管氢等离子体微波吸收的影响,运用转移矩阵法求解电磁波的传播方程,计算不同条件下碳纳米管氢等离子体薄膜在0~30GHz频段的微波衰减系数。随着氢等离子体中自由电子密度分布非均匀性系数a的增加,微波衰减吸收峰值|Attmax|和强烈微波吸收的频宽均明显增大,吸收峰向高频方向移动。结果表明,增大等离子体密度分布的非均匀性,能显著改善碳纳米管氢等离子体薄膜的微波吸收性能。     

Diameter-Selective Raman Scattering from Vibrational Modes in Carbon Nanotubes

Single wall carbon nanotubes (SWNTs) that are found as close-packed arrays in crystalline ropes have been studied by using Raman scattering techniques with laser excitation wavelengths in the range from 514.5 to 1320 nanometers. Numerous Raman peaks were observed and identified with vibrational modes of armchair symmetry (n, n) SWNTs. The Raman spectra are in good agreement with lattice dynamics calculations based on C-C force constants used to fit the two-dimensional, experimental phonon dispersion of a single graphene sheet. Calculated intensities from a nonresonant, bond polarizability model optimized for sp2 carbon are also in qualitative agreement with the Raman data, although a resonant Raman scattering process is also taking place. This resonance results from the one-dimensional quantum confinement of the electrons in the nanotube.     

碳纳米管在农业中的应用研究进展

碳纳米管为一种新型纳米材料,在新能源、新材料、生物传感器等诸多领域得到广泛关注和应用。由于其具有优异的跨膜能力和吸附效应等优点,在农业上也得到广泛关注和应用。综述了碳纳米管在植物生长发育调控、植物病害防治及环境保护等方面的作用,探讨了其在农业上的应用前景,为利用碳纳米管调节植物生长发育、防治植物病害、消除环境污染奠定基础。     

均匀磁场中碳纳米管的电子结构

采用π电子紧束缚近似方法,对处于稳定磁场中考虑电子自旋情况下的单壁碳纳米管的电子结构进行了理论分析.发现磁场中的SWNTs的子能带和磁通量是量子化的,其子能带以Φ0为周期随Φ作周期性变化;并出现了金属-半导体的周期性转变现象.     

基于羧基化碳纳米管检测磺酰胺的电化学传感方法研究

[目的]磺胺类药物是一类广谱抗菌药,在畜禽和水产养殖临床都被广泛应用,其在食品中残留对消费者健康会造成一定的潜在危害,因此研究简便、快速、高灵敏度的检测方法十分必要.[方法]研究建立了一种检测磺酰胺的电化学传感方法.首先采用差分脉冲(differential pulse voltammetry,DPV)法筛选了7种工作电极修饰材料,发现磺酰胺在羧基化碳纳米管(COOH-CNTs)修饰的工作电极上有最大的峰电流响应,进一步通过电化学阻抗和电催化有效表面积研究了COOH-CNTs修饰电极的电化学性能,然后优化了修饰材料在玻碳电极上的滴涂体积和检测缓冲液pH等条件.[结果]筛选的7种不同的修饰材料中,磺酰胺在COOH-CNTs修饰的电极峰电流响应最大(11.89μA),且催化电位相对于其他的修饰材料最低(0.76 V),说明COOH-CNTs对磺酰胺的氧化具有最好的电催化作用.其次是掺氮石墨烯(N-Gr),最差的是羧基化石墨烯(COOH-Gr);阻抗实验表明COOH-CNTs修饰后的奈奎斯特半圆的直径较未修饰的玻碳电极明显更小,表明修饰后的电极电子传递能力大大提高了.以修饰材料COOH-CNTs用量为5μL,检测缓冲液pH为8.5条件下,磺酰胺在9.29×10-6～2.9×10-4 mol/L呈良好的线性关系,线性回归方程为:y=0.0087x+0.0955,相关系数R2=0.9916,检测限为6.21×10-6 mol/L,加标回收率在91.48％～105.32％,电极重复使用12次的RSD为1.99％.[结论]本实验筛选到了一种对磺酰胺响应灵敏度高的电极修饰材料COOH-CNTs,建立了简便、快速、稳定性好的电化学检测方法,该方法适用于草鱼和鲜奶样品中磺酰胺药物残留检测.     

MATERIALS SCIENCE: Putting a New Spin on Carbon Nanotubes

Nanotube fibers are expected to have a wide range of applications from energy storage to high-strength mechanical devices. But as Baughman explains in his Perspective, methods for making such fibers have been of limited success. In contrast, the process reported by Vigolo et al. shows great promise. Together with a recently reported, more economically viable nanotube production process, this method may open the door to large-scale devices and materials based on carbon nanotubes.     

基于非局部弹性理论的碳纳米管振动特性研究

基于非局部弹性理论,建立了碳纳米管壳体模型的应力应变关系.根据基本方程和平衡条件,分别给出了单壁和多壁碳纳米管动力学控制微分方程;通过对动力学方程求解,获得了碳纳米管振动的固有频率.研究结果表明:随着振动模式的增加,碳纳米管的振动基频都会增大;而随着碳纳米管的长度或直径的增大,碳纳米管的振动基频都会降低.     

多壁碳纳米管表面邻二氯苯分子印迹聚合物材料的制备

在多壁碳纳米管表面接枝碳碳双键,以邻二氯苯为模板、苯乙烯为功能单体、乙二醇二甲基丙烯酸酯为交联剂,采用沉淀聚合技术,在碳纳米管表面制备邻二氯苯印迹材料,用红外光谱、热重分析、透射电镜对材料性能进行表征。结果表明,在碳纳米管表面接枝一层稳定、均匀、30～50 nm厚的印迹材料。用高效液相色谱研究该印迹材料的吸附动力学及吸附容量,结果表明,印迹材料的吸附平衡时间为100 min,通过Scatchard分析,该聚合物与邻二氯苯的结合位点有2个,最大吸附容量为92.732 mol/g,平衡常数为17.986 mol/L,表明能成功将该材料用于检测环境中邻二氯苯的前处理。     

磁性碳纳米管吸附去除水中蒽的研究

利用化学共沉淀方法制备了磁性多壁碳纳米管,研究了磁性多壁碳纳米管对水中蒽的吸附行为及pH值、离子强度、腐殖酸等因素的影响.结果表明,在弱酸性条件下其吸附效率最高,离子强度对吸附的影响较小,腐殖酸在低浓度时抑制蒽的吸附,高浓度腐殖酸则可以促进吸附;蒽的吸附过程符合准二级动力学方程;磁性多壁碳纳米管对蒽的吸附率超过98%,最大吸附量可达到95.2mg/g,能有效地去除水中的蒽.     

几种碳纳米管对小鼠呼吸系统的影响

[目的]表征几种碳纳米管（CNTs）的特性,并检测其对呼吸系统的毒性。[方法]运用透射电镜、拉曼光谱技术检测市售几种碳纳米管的性状;通过染毒箱研究CNTs对小鼠呼吸系统的影响。[结果]单壁碳纳米管（SWCNTs）对呼吸系统的影响小,多壁碳纳米管（MWCNTs）对呼吸系统的影响较大。[结论]CNTs对呼吸系统的影响和杂质的含量与管壁的直径有关。     

单壁碳纳米管的扭曲形变对氢吸附的影响

用基于DFT理论的第一性原理对扭曲形变的碳纳米管吸附氢的计算.通过计算不同手性的碳纳米管的结合能,得到了不同手性的碳纳米管对氢有着不同的吸附能.(6,6)型的碳管对氢的吸附性能力远强于(9,0)型的碳管.此外,碳管发生扭曲形变之后显著地提高了对氢的吸附能力,且其对氢的吸附能力与碳管的扭曲形变程度有很大的关系.