由煤或焦炭制备纳米碳质材料的新进展

评述了以煤为碳源制备富勒烯、纳米碳管、竹节形碳管、铁嵌入的纳米碳棒和由碳包覆的金属纳米粒子等各种纳米材料。认为：等离子体电孤放电法是由煤制备各种纳米碳质材料最常用的方法，随电弧条件及电极性质的不同，所制备的纳米碳质材料可有各种不同形态及结构、由于煤是分子固体而石墨是晶格固体，两种碳源的反应机理有明显不同。在等离子体电弧加热时，煤分解并产生许多具有简单芳烃结构的分子，在纳米碳质材料的形成过程中，这些分子可能作为纳米碳质材料的结构单元，同时原煤中的矿物质在合成过程中也起着重要作用，因此煤本身的性质对纳米材料的制备极为重要。煤是成本低廉且储量最丰富的碳源，将是大规模工业化生产纳米碳质材料最好的碳源之一。     

Inorganic nanotubes

Following the discovery of carbon fullerenes and carbon nanotubes, it was hypothesized that nanoparticles of inorganic compounds with layered (two-dimensional) structure, such as MoS(2), will not be stable against folding and form nanotubes and fullerene-like structures: IF. The synthesis of numerous other inorganic nanotubes has been reported in recent years. Various techniques for the synthesis of inorganic nanotubes, including high-temperature reactions and strategies based on 'chemie douce' (soft chemistry, i.e. low-temperature) processes, are described. First-principle, density functional theory based calculations are able to provide substantial information on the structure and properties of such nanotubes. Various properties of inorganic nanotubes, including mechanical, electronic and optical properties, are described in brief. Some potential applications of the nanotubes in tribology, protection against impact, (photo)catalysis, batteries, etc., are discussed.     

过渡族金属硫化物纳米管结构研发现状

随着碳富勒烯和碳纳米管的发现,具有类似层状结构的纳米颗粒MoS2,由于片层状平面结构的不稳定,易形成封闭多面体笼状结构和管状结构.综述了过渡族金属硫化物MS2(M=W,Mo,Nb,Ta,Zr,Ti,Re,Hf)纳米管的合成方法、微观结构、生长机制及其潜在的性能和应用.     

Fullerenes with Non-Positive Gaussian Curvature: Holey-Balls and Holey-Tubes

Classical fullerenes such as C₆₀ and C₇₀ need 12 pentagonal rings of carbon for the closure of the cage. These pentagons produce the positive Gaussian curvature which gives the characteristic spherical shape. In this paper we propose a new family of fullerene-like structures which do not have pentagonal rings (no positive Gaussian curvature), no dangling bonds, possesing hexagons and heptagons only. The topology of this new family of perforated fullerenes (holey-balls) and nanotubes (holey-tubes) is higher than classical fullerenes presenting genus 5, 11 up to 21. Holey balls can be icosahedral (I_h) and cubic (O_h). The geometry, elastic stabilities and possible applications of holey-balls and holey-tubes are studied.     

A novel hybrid carbon material

Both fullerenes and single-walled carbon nanotubes (SWNTs) exhibit many advantageous properties. Despite the similarities between these two forms of carbon, there have been very few attempts to physically merge them. We have discovered a novel hybrid material that combines fullerenes and SWNTs into a single structure in which the fullerenes are covalently bonded to the outer surface of the SWNTs. These fullerene-functionalized SWNTs, which we have termed NanoBuds, were selectively synthesized in two different one-step continuous methods, during which fullerenes were formed on iron-catalyst particles together with SWNTs during CO disproportionation. The field-emission characteristics of NanoBuds suggest that they may possess advantageous properties compared with single-walled nanotubes or fullerenes alone, or in their non-bonded configurations.     

Formation and conversion of carbon nanostructures under radiation

Consideration has been given to the current status of research on the use of radiation techniques for synthesizing new carbon nanomaterials based on fullerenes, carbon nanotubes, and graphene sheets and their derivatives, which are promising for practical application due to their unique properties. An analysis has been made of the existing experimental and theoretical works on studying different processes induced by the action of radiation on carbon nanostructures (melting of cross-linking carbon nanotubes and formation of molecular junctions between them, polymerization of fullerene layers, formation of new structures, radiation chemistry of fullerenes, and others).     

Quantification of ion trapping effect of carbon nanomaterials in liquid crystals

We have determined the ion trapping coefficients of carbon nanomaterials in liquid crystals through the analysis of capacitance-voltage response. The ion trapping coefficient is defined as the ability to trap impurity ions for each carbon nanomaterial and can be used as a referable value to select proper carbon nanomaterials as dopants in liquid crystals. The characterized nanomaterials include multi-wall carbon nanotubes, carbon nanofibers, carbon nanocoils, single-wall carbon nanotubes and fullerenes, respectively. It is found that the multi-wall carbon nanotubes with a tube length of 5-15 μm have the largest ion trapping coefficient and hence serve as the best dopant to suppress the liquid crystal hysteresis.     

Novel Nanocarbons—Structure,Properties, and Potential Applications

The 1985 discovery of the third form of ordered carbon, commonly known as the fullerenes, spurred the subsequent discovery of a number of related novel forms of carbon. The most famous among these carbons are the nanotubes, sometimes referred to as buckytubes as well. In this review, I discuss the structure, properties, and potential applications of most of these novel carbons. It is also interesting to examine how the various forms of nanocarbons are related to one another, and the conditions under which one form transforms to another. From the vast amount of research that has been carried out over the last decade, it is apparent that some of these nanocarbons would have extremely unique properties that might be of value for specific applications that are being contemplated by various researchers. The real breakthrough for this technology would be new processing methods to produce such novel structures in commercial quantities.     

A New Molecular Mechanics Computer Program for Giant Fullerenes and Nanotubes

The molecular mechanics computer program is designed to study the structure of fullerenes with icosahedral symmetry and carbon nanotubes. The program takes full advantage of symmetry. The program predicts meaningful conformations, energies of formation for symmetrical fullerenes as well as for the carbon nanotubes for which also the elastic properties are calculated.

The systematic IUPAC nomenclature of fullerenes and fullerenes derivatives is discussed. Comments are made on terminology questions and on the chemical non-aromaticity of fullerenes.     

Inorganic nanotubes and fullerene-like nanoparticles

Although graphite, with its anisotropic two-dimensional lattice, is the stable form of carbon under ambient conditions, on nanometre length scales it forms zero- and one-dimensional structures, namely fullerenes and nanotubes, respectively. This virtue is not limited to carbon and, in recent years, fullerene-like structures and nanotubes have been made from numerous compounds with layered two-dimensional structures. Furthermore, crystalline and polycrystalline nanotubes of pure elements and compounds with quasi-isotropic (three-dimensional) unit cells have also been synthesized, usually by making use of solid templates. These findings open up vast opportunities for the synthesis and study of new kinds of nanostructures with properties that may differ significantly from the corresponding bulk materials. Various potential applications have been proposed for the inorganic nanotubes and the fullerene-like phases. Fullerene-like nanoparticles have been shown to exhibit excellent solid lubrication behaviour, suggesting many applications in, for example, the automotive and aerospace industries, home appliances, and recently for medical technology. Various other potential applications, in catalysis, rechargeable batteries, drug delivery, solar cells and electronics have also been proposed.     

Simulation of novel superhard carbon materials based on fullerenes and nanotubes

The state-of-the-art in theoretical research directed at the search for superhard materials based on carbon fullerenes and nanotubes has been briefly reviewed. The data available on elastic properties of the main groups of condensed phases that form due to the interaction of fullerenes or (and) nanotubes because of both weak (of the van der Waals type) bonds and polymerization to form strong covalent sp3 bonds have been considered. Models for new hypothetical carbon nanostructured materials (the so-called autointercalated hyperdiamonds, covalently bonded lattices of nanotubes, tubular cubic crystals, etc.) are discussed, and elastic properties of them are considered as related to their atomic structure, special features of their electronic structure and chemical bond have been discussed. The problems of synthesis of these systems are briefly considered.     

Predictions of novel nanostructures of silicon by metal encapsulation

Recent studies using ab initio total energy calculations have shown exciting possibilities of developing novel metal encapsulated caged clusters of silicon with fullerene-like, Frank–Kasper and other polyhedral structures. In contrast to carbon for which empty cage fullerene structures are stable with 20 or more atoms, 10–16 atom silicon cage structures are stabilized by a guest metal atom. These nanoclusters are predicted to exhibit luminescence in the visible range and could find applications in biological systems, optoelectronics, and as tagging material. The Raman and infrared spectra have been calculated and they could help in the experimental identification of the structures. Interaction of these clusters with metal as well as oxygen or hydrogen atoms show that the fullerene structure is stable. Also the interaction between clusters themselves is weak and the ionization potentials, large. These properties make them attractive for cluster assembled materials such as nanowires, nanotubes, and other 2 and 3D structures. Studies on hydrogen interaction have led to the predictions of empty center hydrogenated silicon fullerenes Si_nH_n with large HOMO–LUMO gaps. These could further be doped endohedrally or exohedrally to produce novel silicon fullerenes with a variety of properties opening new ways of using silicon for diverse applications.     

Recent Progress on Fabrications and Applications of Boron Nitride Nanomaterials:A Review

Boron nitride(BN) nanostructures with complementary functions to their carbon counterparts are one of the most intriguing nanomaterials.Here we devote a compact review on the syntheses of BN nanomaterials:typical zero-dimensional(OD) fullerenes and nanoparticles,one-dimensional(1D) nanotubes and nanoribbons,two-dimensional(2D) nanosheets as well as three-dimensional(3D) nanoporous BN.Combining low-dimensional quantum confinement and surface effects with unique physical and chemical properties of BN,e.g.excellent electric insulation,wide band gap,and high chemical and thermal stability,BN nanomaterials have drawn particular attention in a variety of potential applications,e.g.luminescence,functional composites,hydrogen accumulators,and advanced insulators,which are also reviewed.     

Carbon nanomaterials for advanced energy conversion and storage

It is estimated that the world will need to double its energy supply by 2050. Nanotechnology has opened up new frontiers in materials science and engineering to meet this challenge by creating new materials, particularly carbon nanomaterials, for efficient energy conversion and storage. Comparing to conventional energy materials, carbon nanomaterials possess unique size-/surface-dependent (e.g., morphological, electrical, optical, and mechanical) properties useful for enhancing the energy-conversion and storage performances. During the past 25 years or so, therefore, considerable efforts have been made to utilize the unique properties of carbon nanomaterials, including fullerenes, carbon nanotubes, and graphene, as energy materials, and tremendous progress has been achieved in developing high-performance energy conversion (e.g., solar cells and fuel cells) and storage (e.g., supercapacitors and batteries) devices. This article reviews progress in the research and development of carbon nanomaterials during the past twenty years or so for advanced energy conversion and storage, along with some discussions on challenges and perspectives in this exciting field.     

Irradiation of carbon nanotubes with a focused electron beam in the electron microscope

The paper reviews in-situ electron irradiation studies of carbon nanotubes in electron microscopes. It is shown that electron irradiation at high specimen temperature can lead to a variety of structural modifications and new morphologies of nanotubes. Radiation defects such as vacancies and interstitials are created under irradiation, but the cylindrically closed graphene layers reconstruct locally and remain coherent. The generation of curvature in graphene layers with non-hexagonal rings allows us to alter the topology of nanotubes. Several examples of irradiation-induced modifications of single- and multi-wall nanotubes are shown. Conclusions about the mobility of interstitials and vacancies are drawn which are important to explain the behaviour and the properties of nanotubes with an atomic arrangement deviating from the hexagonal network of graphene.     

Effect of constructive rehybridization on transverse conductivity of aligned single-walled carbon nanotube films

Alignment of densely packed single-walled carbon nanotubes (SWNTs) largely preserves the extraordinary electronic properties of individual SWNTs in the alignment direction, while in transverse direction the films are very resistive due to large energy barriers for tunneling between adjacent SWNTs. We demonstrate that chromium atoms inserted between the sidewalls of parallel SWNTs effectively coordinate to the benzene rings of the nanotubes via hexahapto bonds that preserve the nanotube-conjugated electronic structure and serve as a conduit for electron transfer. The atomically interconnected aligned SWNTs exhibit enhanced transverse conductivity, which increases by ～2100% as a result of the photoactivated organometallic functionalization with Cr. The hexahapto mode of bonding the graphitic surfaces of carbon nanotubes with transition metal atoms offers an attractive route to the reversible chemical engineering of the transport properties of aligned carbon nanotube thin films. We demonstrate that a device fabricated with aligned SWNTs can be reversibly switched between a state of high electrical conductivity (ON) by light and low electrical conductivity (OFF) by applied potential. This study provides a route to the design of novel nanomaterials for applications in electrical atomic switches, optoelectronic and spintronic devices.     

Characteristics of multi-walled carbon nanotubes and background aerosols by carbon analysis; particle size and oxidation temperature

Novel carbonaceous nanomaterials such as carbon nanotubes and fullerenes have many beneficial characteristics as industrial materials, but exposure to these nanomaterials also poses health risks. As part of an exposure assessment, we characterized the following carbonaceous nanomaterials, using an aerosol carbon monitor: nine samples of multi-walled carbon nanotubes (MWCNTs), a sample of single-walled carbon nanotubes (SWCNTs), a standard sample of diesel exhaust particles (DEPs), and an ambient particulate matter (APM). The amounts of elemental carbon (EC) determined by the monitor coincided with the mass of MWCNTs calibrated by a microbalance. The carbonaceous nanomaterials were oxidized in three steps of oven temperatures (550, 700 and 920 °C) in this method. The portion of oxidized carbon at each temperature depended on the sample characteristic. We used the monitor to analyze the aerosol samples collected in five stages by a Sioutas cascade impactor (SCI), which collects size-segregated airborne particles having aerodynamic diameters from 6.6 μm to less than 0.25 μm. As MWCNTs aggregate/agglomerate easily, the size was of a good parameter to distinguish the MWCNTs from other materials. Two-dimensional mapping by size and oxidized temperature suggested the origin of the carbonaceous aerosol samples. Based on the results, we reanalyzed our previous data obtained at a factory manufacturing MWCNTs. The characteristics of workplace samples by particle size and carbon analysis were similar to those of MWCNT aerosol particles.     

Modulation of structural and electronic properties of fullerene and metallofullerenes by surface chemical modifications

Many applications of fullerene, metallofullerene, and carbon nanotubes request the chemical modifications. But how the modification influences the stability, structural, and electronic properties that directly relate to the practical functions of the carbon nanomaterials, this issue is discussed in this paper. The outer chemical modifications can sensitively influence the stability of final derivatives of fullerenes, depending on parameters such as the number of the modified groups, the unintended impurity groups on the cage surface, and chemical conditions in synthesizing processes. The outer chemical modification can induce alteration in electronic properties of metallofullerene. Gd@C82 is taken as a model to show how the electronic properties of the encaged metal atom are modulated by the cage surface modification. There exist sandwich-type electronic interactions along pathway: [outer modification group]-[cage surface]-[inner atom], and their synergistic effects are discussed. Beside the number of the modified groups, whose distribution patterns on the cage surface also play crucial roles in determining how the electronic interactions are modulated. Their synergistic effects dominate the electronic, optical, or magnetic properties of functionalized fullerenic nanomaterials. As the surface of nanotube is chemically more inert as compared to that of fullerene or metallofullerene, to achieve desirable modulations of nanotubes is probably more difficult. The research aimed to explore the changes in their structural or electronic property after the outer chemical functionalization was few, though this is of special significant and needs investigations because the chemical modifications are widely applying to the carbon nanotubes in applications.     

Analysis of stress responsive genes induced by single-walled carbon nanotubes in BJ Foreskin cells

Nanotechnology is finding its use as a potential technology in consumer products, defense, electronics, and medical applications by exploiting the properties of nanomaterials. Single-walled carbon nanotubes are novel forms of these nanomaterials with potential for large applications. However, the toxicity studies on this material are not explored in detail and therefore limiting its use. It has been earlier reported that single-walled carbon nanotubes induces oxidative stress and also dictates activation of specific signaling pathway in keratinocytes. The present study explores the effect of single-walled carbon nanotubes on stress genes in human BJ Foreskin cells. The results show induction of oxidative stress in BJ Foreskin cells by single-walled carbon nanotubes and increase in stress responsive genes. The genes included inducible genes like HMOX1, HMOX2, and Cyp1B1. In addition we validated increase for four genes by SWCNT, namely ATM, CCNC, DNAJB4, and GADD45A by RT-PCR. Moreover results of the altered stress related genes have been discussed and that partially explains some of the toxic responses induced by single-walled carbon nanotubes.