Optical properties and photonic devices of doped carbon nanotubes

Chemical doping of carbon nanotubes provides a variety of opportunities for tailoring the physical properties of carbon nanotubes. In this review, we discussed the optical properties of doped carbon nanotubes and the related applications as nanoscale photonic devices. The fundamental optical properties of carbon nanotubes with various chemical doping have been summarized. Novel optoelectronic and photonic devices based on doped carbon nanotubes, such as optical nonlinear materials, optical limiting devices, photovoltaic devices, etc., have been discussed.     

Chemically Modified Carbon Nanotubes for Use in Electroanalysis

The discovery of carbon nanotubes has had a profound impact on many areas of science and technology, not least that of electroanalysis. The properties and applications of carbon nanotubes themselves have been well reviewed in the literature and a number of reviews with an electrochemical emphasis have been published. However, the modification of carbon nanotubes has recently been the focus of much research, primarily to improve their solubility in various solvents. Yet modified carbon nanotube electrodes also allow the electrochemist to tailor the properties of the carbon nanotubes, or the electrode surface to impart desired properties such as enhanced sensing capabilities. In this review we attempt to comprehensively cover the different chemical and electrochemical modification strategies and research carried out using modified carbon nanotubes for electroanalytical and bioanalytical applications. Furthermore we also discuss the use of modified carbon nanotubes in electrocatalysis and biocatalysis from an analytical aspect, as well as seeking to dispel some of the myths surrounding the “electrocatalytic” properties of carbon nanotubes.     

纳米碳管表面羧基化及其电还原性能

应用红外吸收光谱、扫描电子显微镜分别对纳米碳管和硝化后的纳米碳管进行表征,将其制备成粉末微电极,并在碱性溶液中测试它对对硝基苯酚的电还原性能.实验表明:经硝化处理后,碳管表面修饰了羰基,其电还原性能明显提高.依据实验结果探讨了硝化后纳米碳管于对硝基苯酚电还原过程中的反应机理.     

碳纳米管及碳纤维增强环氧树脂复合材料研究进展

碳纳米管与碳纤维具有优异的力学、电学等性能,广泛用做复合材料增强体,但目前碳纳米管/碳纤维/环氧树脂复合材料的研究具有一定的局限性,只考虑了两相材料间的作用,即仅对单一相进行处理而忽略了另一相的改性。本文从碳纳米管/碳纤维协同增强环氧树脂基体复合材料的思路入手,结合自己的研究成果,综述了国内外相关研究进展。从研究结果可以看出,将三相材料之间完全有效地联系起来,发挥三者间的协同效应,复合材料的性能可以发生质的飞跃。     

碳纳米管共价功能化

碳纳米管由于其独特的结构与优异的各项性能,在许多领域具有巨大的应用潜力,已引起了广泛的关注。由于碳纳米管不溶于水和有机溶剂,极大地制约了其性能应用,因此碳纳米管的功能化就成为目前研究的热点。本文侧重于碳纳米管的共价功能化,详细讨论了碳纳米管不同位置共价功能化的研究进展。     

Polyoxometalate-modified carbon nanotubes: new catalyst support for methanol electro-oxidation

A new catalyst support, polyoxometalate-modified carbon nanotubes, is presented in this paper through the chemisorption between polyoxometalate and carbon. Pt and Pt-Ru nanoparticles were electrochemically deposited on polyoxometalate-modified carbon nanotubes electrodes, and their electrocatalytic properties for methanol electro-oxidation are investigated in detail. Due to the unique electrical properties of carbon nanotubes and the excellent redox properties and the high protonic conductivity of polyoxometalate, for the similar deposition charge of Pt and Pt-Ru catalysts, 1.4 times larger exchange current density, 1.5 times higher specific activity, and better cycle stabilities can be obtained at polyoxometalate-modified carbon nanotube electrodes as compared to the electrodes without polyoxometalate modification. These results show that polyoxometalate-modified carbon nanotubes as a new catalyst support have good potential application in direct methanol fuel cells.     

碳纳米管在水中的分散性

以超声波为辅助工具,分别研究阳离子、阴离子型等表面活性剂在水中对碳纳米管分散性的影响,进而研究两种表面活性剂复配后对碳纳米管分散性的影响。通过记录分散的碳纳米管溶液的保存时间和SEM对分散效果进行分析和观察。     

Aligned Nanotubes

Since the discovery of carbon nanotubes by Iijima in 1991, various carbon nanotubes with either a single‐ or multilayered graphene cylinder(s) have been produced, along with their noncarbon counterparts (for example, inorganic and polymer nanotubes). These nanostructured materials often possess size‐dependent properties and show new phenomena related to the nanosize confinement of the charge carriers inside, which leads to the possibility of developing new materials with useful properties and advanced devices with desirable features for a wide range of applications. In particular, carbon nanotubes have been shown to exhibit superior properties attractive for various potential applications, ranging from their use as novel electron emitters in flat‐panel displays to electrodes in electrochemical sensors. For many of the applications, it is highly desirable to have aligned/patterned forms of carbon nanotubes so that their structure/property can be easily assessed and so that they can be effectively incorporated into devices. In this Review, we present an overview on the development of aligned and micropatterned nanotubes, with an emphasis on carbon nanotubes.     

Electrochemical Sensors Based on Carbon Nanotubes

Carbon nanotubes are attractive new materials. It has been about a decade since carbon nanotubes were discovered. Carbon nanotubes have many outstanding properties and have many practical or potential applications. In this short review we introduce recent advances in carbon nanotubes as potential material for electrochemical sensors. The advantages of carbon nanotubes as sensors are discussed along with future prospects.     

尼龙/碳纳米管复合材料研究进展

碳纳米管(CNTs)由于其独特的结构,较高的长径比,较大的比表面积,且具有超强的力学性能和良好的导热性,已经证明是塑料的非常优异的导电填料,聚合物基碳纳米管复合材料可望应用于材料领域的多个方面,尤其在汽车、飞机及其它飞行器的制造等军事和商业应用上带来革命性的突破。本文介绍了碳纳米管的结构形态和碳纳米管的制备、纯化、修饰方法及聚合物基碳纳米管复合材料的制备、性能,并综述了近几年来尼龙/碳纳米管复合材料的研究进展及应用前景。     

Skin Constituents as Cosmetic Ingredients. Part III: A Molecular Modeling Study of Bio‐Mimetic Monoglycerides Behavior at the Squalene‐Water Interface

Tetrakis(4-hydroxylphenyl)porphyrin (THPP) modified multi-walled carbon nanotubes were synthesized. Meanwhile, THPP or tetrakis(4-hydroxylphenyl)porphyrin cobalt(II) (CoTHPP) was introduced on the surface of carboxyl-functionalized multi-walled carbon nanotubes (MWNTs-COOH) and amino-functionalized multi-walled carbon nanotubes (MWNTs-NH₂) to form a series of complexes, respectively. TEM images indicated that the assemblies were made of the short chipping carbon nanotubes and the long assembled carbon nanotubes. The UV-vis spectra and fluorescence spectra were used to investigate the properties of the porphyrins assembled on the carbon nanotubes.     

功能化碳纳米管的电磁性能研究及进展

碳纳米管是最近发展起来的一种结构独特,性能优异的新材料,已成为当今物理、化学、材料等领域共同关注的课题.而碳纳米管的功能化更是为我们开辟了一个广阔的研究领域.本文总结了近十多年来功能化碳纳米管的研究进展,并侧重对功能化碳管的合成方法及电磁特性以及应用进行了评述.     

Study on Diameter Controlled Growth of Carbon Nanotubes by LaAl1-xFexO3 Catalysts

A series of LaAl1-xFexO3 catalysts prepared with lanthanum nitrate, aluminium nitrate and iron nitrate was investigated in catalytical syntheses of carbon nanotubes with high yields and purity. The properties of carbon nanotubes prepared by the method of CVD(chemical vapor deposition) with n-hexane as the carbon resource were studied and it was shown that the diameter of carbon nanotubes can be controlled by the molar ratio of iron to aluminum in the catalysts and that the diameter of carbon nanotubes changes a little with the decrease of the iron content in the catalysts. From the TEM pictures of carbon nanotubes, it can be found that the LaAl1-xFexO3 catalysts have a significant influence on the wall thickness of the carbon nanotubes, whereas they have little influence on the inner diameter of the carbon nanotubes.     

Generation of hydrophilic, bamboo-shaped multiwalled carbon nanotubes by solid-state pyrolysis and its electrochemical studies

A simple, efficient, and novel method was developed for the direct preparation of hydrophilic, bamboo-shaped carbon nanotubes by the pyrolysis of ruthenium(III) acetylacetonate in a Swagelock cell is reported. The obtained product exhibits mostly bamboo-shaped, straight, periodic twisted, multiwalled carbon nanotubes possessing diameters of 50-80 nm and lengths of around 10 microm. The pyrolyzed product was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), micro-Raman, and cyclic voltammetric techniques. HRTEM studies showed that the walls of bamboo-shaped carbon nanotubes consisted of oblique grapheme planes with respect to the tube axis. The interlayer spacing between two graphitic layers was found to be 0.342 nm. XPS measurements have suggested that as-prepared carbon nanotubes consist the surface functional groups on the surface of carbon nanotubes. The electrochemical properties of synthesized carbon nanotubes have been evaluated. Thermogravimetric analysis (TGA), IR, and cyclic voltammetric studies showed the presence of oxygen functionalities. Raman studies revealed the presence of disorder in the graphitic carbon and the presence of exposed edge plane defects in the generated carbon nanotubes for influencing the surface behavior and electrochemical properties. The electrochemical behavior of electrodes made of bamboo-shaped carbon nanotubes served for an oxygen reduction reaction.     

碳纳米管的定向操作

由于呈现独特的一维结构特征、机械及电子性能,碳纳米管已引起广泛的兴趣,然而涉及到具体的应用就不可避免碳纳米管的定位、定向,这也已成为非常富有挑战性的课题。本文中笔者主要介绍碳纳米管定向操作的最新进展,重点介绍后生长的平面有序定向操作。     

Influence of Electric Field on Dispersion of Carbon Nanotubes in Liquids

Production processes for carbon nanotubes commonly produce mixtures of solid morphologies that are mechanically entangled or that self‐associate into aggregates. The entangled or aggregated carbon nanotubes often need to be dispersed in corresponding material matrices in order to develop materials that have unique mechanical characteristics or transport properties. The most effective method for dispersion of carbon nanotubes is to prepare fluid suspensions of them in liquid media with applications of surfactant or/and ultrasonication. The authors propose an innovative dispersion method for carbon nanotubes by which an electric field is applied to suspensions of carbon nanotubes in liquids treated by surfactant and ultrasonication. Compared to dispersion without the electric field, the dispersion status of carbon nanotubes in liquid media is evidently improved with the electric field. The results indicate that the electric field conditions are effective for dispersion of carbon nanotubes in liquids and that complex effects of electric field, surfactant, and ultrasonication are beneficial for improvement of dispersion of carbon nanotubes.     

Polymer-masking for controlled functionalization of carbon nanotubes

An effective and versatile method for tube-length-specific functionalization of carbon nanotubes through a controllable embedment of vertically-aligned carbon nanotubes into polymer matrices is reported, which allows not only asymmetric functionalization of nanotube sidewalls, but also facile introduction of new properties (e.g. magnetic) onto the region-selectively functionalized carbon nanotubes.     

Degradation of physicomechanical properties of epoxy nanocomposites with carbon nanotubes upon heat and humidity aging

The dependence of the physicomechanical properties of epoxy nanocomposites subjected to heat and humidity aging on the type of covalently functionalized carbon nanotubes and on the uniformity of their distribution in the epoxy matrix was studied. Two types of carbon nanotubes were used: those modified with carboxy and amide groups. The elastic modulus, bending deflection, and ultimate bending strength for the initial epoxy nanocomposites with carbon nanotubes and for those subjected to heat and humidity aging were determined. The epoxy binders modified with carboxylated carbon nanotubes are more resistant to the action of aging factors. The presence of aggregates of carboxylated carbon nanotubes in the epoxy matrix positively influences the preservation of physicomechanical properties of the composite subjected to heat and humidity aging. Microscopic examination revealed structural features of the epoxy nanocomposite and their effect on the resistance of the composite to the heat and humidity aging.     

Constrained iron catalysts for single-walled carbon nanotube growth

The diameter of single walled carbon nanotubes (SWNTs) determines the electronic properties of the nanotube. The diameter of carbon nanotubes is dictated by the diameter of the catalyst particle. Here we describe the use of iron nanoparticles synthesized within the Dps protein cage as catalysts for the growth of single-walled carbon nanotubes. The discrete iron particles synthesized within the Dps protein cages when used as catalyst particles gives rise to single-walled carbon nanotubes with a limited diameter distribution.     

Use of high-purity metal-catalyst-free multiwalled carbon nanotubes to avoid potential experimental misinterpretations

Carbon nanotubes, even after extensive posttreatment, contain metallic impurities which may produce misleading results, giving rise to false claims of the properties of carbon nanotubes. To overcome this, we report on high-purity catalyst-free multiwalled carbon nanotubes which have been explored with transmission electron microscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry using the electrochemical oxidations of hydrazine and potassium ferrocyanide. The multiwalled carbon nanotubes are approximately 150 nm in length and consist of 6-10 graphite layers. Due to the definitive absence of metallic impurities, experimentalists using these carbon nanotubes can avoid potential misinterpretations of their results.