Fullerenes and Nanotubes from Coal

Graphite has normally been used to synthesise fullerenes and nanotubes. However, coal is a cheaper and more suitable industrial material. Because coal is a molecular solid, unlike graphite, the mechanism by which fullerene and nanotubes are formed is different. Moreover, other products such as polyaromatic hydrocarbons (PAHs) and microfibres are also formed. In this review, the mechanism of formation of fullerene and nanotubes from coal is discussed. It is shown that the pathway involved is other than through the C₁ intermediate route. The influence of other elements in coal such as hydrogen, oxygen, sulfur and iron is also discussed. It appears that, hydrogen, oxygen, iron and sulfur affect the yield and type of fullerenes and nanotubes formed.     

Fullerenes and Nanotubes from Coal

Abstract

Graphite has normally been used to synthesise fullerenes and nanotubes. However, coal is a cheaper and more suitable industrial material. Because coal is a molecular solid, unlike graphite, the mechanism by which fullerene and nanotubes are formed is different. Moreover, other products such as polyaromatic hydrocarbons (PAHs) and microfibres are also formed. In this review, the mechanism of formation of fullerene and nanotubes from coal is discussed. It is shown that the pathway involved is other than through the C₁ intermediate route. The influence of other elements in coal such as hydrogen, oxygen, sulfur and iron is also discussed. It appears that, hydrogen, oxygen, iron and sulfur affect the yield and type of fullerenes and nanotubes formed.     

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.     

GdNi2合金选择性合成Gd金属包合物和单壁碳纳米管

以GdNi2合金为金属源,采用电弧放电法,控制不同的He压选择性地合成了Gd金属富勒烯包合物和单壁碳纳米管.当He压为16kPa时,主要得到Gd金属富勒烯包合物,当He压为80kPa时,选择性获得单壁碳纳米管.     

Fullerenes and Carbon Nanotubes Formed in an Electric Arc at and Above Atmospheric Pressure

[60]Fullerene and carbon nanotubes have been obtained with an electric arc discharge in helium or argon at the pressure of 0.1-3.0 bar (i.e. from -0.9 up to 2.0 bar above the atmospheric pressure, respectively). The yield of the process is about 10 times higher in helium with a maximum at the pressure of 0.2 bar, while in argon the maximum is observed at 0.4 bar. It is not very important, what kind of the inert gas (He or Ar) is used in a process carried out at the atmospheric pressure and higher. In this case, the yield is usually better or comparable with other alternative methods, e.g. the solar furnace synthesis. We found that the oxygen plays a crucial role reducing the yield of fullerenes and carbon nanotubes. Even traces of O₂ must be removed from the reactor chamber, otherwise yellow coloured fullerene derivatives (oxidation products) are formed instead of C₆₀.     

Fullerenes,Carbon Chains,and Interstellar Matter

Spectroscopy of carbon particles, fullerenes, and carbon chain molecules was the subject of a considerable part of my research work, as described in this article. In almost all cases, there existed a tight connection to problems in astrophysics and astrochemistry, aiming at a better understanding of interstellar matter. The bulk synthesis of fullerenes was a by-product of these efforts.     

Shungite Carbon and Fullerenes

Thermpgravimetry method applied to shungite carbon (ShC) was the next step which testified its similarity with fullerenes. Fullerene-like approach suggested earlier was helpful in understanding shungite nature. ShC behavior under heating in air confirmed the structure ordering and its metastability.     

Shungite Carbon and Fullerenes

Abstract

Thermpgravimetry method applied to shungite carbon (ShC) was the next step which testified its similarity with fullerenes. Fullerene-like approach suggested earlier was helpful in understanding shungite nature. ShC behavior under heating in air confirmed the structure ordering and its metastability.     

Study of Fullerenes,Nanotubes and Nanowires by Transmission Electron Microscopy

Abstract

The arc discharge reactor developped by Kratschmer et al^l produces a variety of new carbonaceous solids, including fullerenes and different kinds of graphitic cages of nanometric size, which can be hollow or filled with various materials. Complementary to neutron and X ray diffraction techniques, transmission electron microscopy rapidly appeared among the most important techniques for studying the structures of fullerenes and fullerites^2?6. Very generally, it allows us to obtain diffraction patterns of micronic size crystallites and the different imaging modes provide an unique tool to investigate in real space the morphology of the crystallites, structural defects faults at microscopic and nanometric scales^6?8. It is possible to perform very local chemical analysis and to study chemical environments in order to determine the nature of chemical bonds⁹. Futhermore, it is possible to study phase transitions through in situ experiments^5,10–12 and the behaviour of fullerites upon electron irradiation¹³. The interest of this technique has appeared even more crucial with the discovery of narotubes¹⁴ and their ability to be filled¹⁵ since, because of their nanometric size, the electron microscopy is at the moment the unique tool allowing their study and is therefore a challenge in the development of these new materials for applications in nanotechnology.     

Influence of Carbon Forms and Doped Elements in the Electrodes for the Production of Fullerenes

Production of fullereries using electrodes made of four kinds of pure carbon bearing materials and artificial graphite doped with seven kinds of elements such as B, Y, La, Gd, Ce, Pr and Nd have been examined. The yields of fullerenes were in a range between 12-20% of the soot produced for all pure carbon electrodes, even though the vaporization rate of amorphous carbon electrodes was about ten times higher than that of the natural graphite electrodes. However, for the doped graphite electrodes, the yield of fullerenes was less than 5%. From the above results it is concluded that fullerenes can be effectively produced with the pure carbon electrodes made of any form of carbon bearing materials used in this study and there is little material dependence on the yield of fullerences. Furthermore, the experiments using the artificaial graphite electrodes doped with metal elements suggests that the purity of the carbon electrodes affects the yeld of fullerenes greatly.     

Study of Fullerenes, Nanotubes and Nanowires by Transmission Electron Microscopy

The arc discharge reactor developped by Kratschmer et al^l produces a variety of new carbonaceous solids, including fullerenes and different kinds of graphitic cages of nanometric size, which can be hollow or filled with various materials. Complementary to neutron and X ray diffraction techniques, transmission electron microscopy rapidly appeared among the most important techniques for studying the structures of fullerenes and fullerites^2-6. Very generally, it allows us to obtain diffraction patterns of micronic size crystallites and the different imaging modes provide an unique tool to investigate in real space the morphology of the crystallites, structural defects faults at microscopic and nanometric scales^6-8. It is possible to perform very local chemical analysis and to study chemical environments in order to determine the nature of chemical bonds⁹. Futhermore, it is possible to study phase transitions through in situ experiments^5,10-12 and the behaviour of fullerites upon electron irradiation¹³. The interest of this technique has appeared even more crucial with the discovery of narotubes¹⁴ and their ability to be filled¹⁵ since, because of their nanometric size, the electron microscopy is at the moment the unique tool allowing their study and is therefore a challenge in the development of these new materials for applications in nanotechnology.     

Heterohedral Fullerenes and Nanotubes: Formation and Characteristics

Both theoretical and experimental studies show that carbon atom(s) can be substituted in a fullerene cage or in a nanotube by “guest” atom(s) or molecule(s) to form stable structures. This new class of networked carbon nanostructures called heterofullerenes and heteronanotubes is presented and their interesting properties and synthesis routes are discussed.     

N2对碳纳米管生长和结构的影响

用热丝化学气相沉积制备了碳纳米管,并用扫描电子显微镜和透射电子显微镜研究了它们的结构.结果表明,用CH4和H2为反应气体制备的碳纳米管是弯曲和中空的,它们的直径较大,生长速率较低;在反应气体中加入N2气后,碳纳米管的平均直径减小,生长速率增大,它们是准直的和竹节型的.分析和讨论了N2对碳纳米管生长和结构的影响.     

衬底温度对碳纳米管生长和结构的影响

用CH4、NH3和H2为反应气体,利用等离子体增强热丝化学气相沉积在沉积有Ta缓冲层和Ni催化剂层的Si衬底上制备了准直碳纳米管,并用扫描电子显微镜和透射电子显微镜研究了它们的生长和结构随温度的变化.结果表明生长的准直碳纳米管是竹节型结构,其直径随衬底温度的降低而减小,生长速率随衬底温度的升高有一极值.从催化剂在衬底温度作用下的变化开始,分析了衬底温度对碳纳米管生长和结构的影响.     

Polyarene‐Functionalized Fullerenes in Carbon Nanotubes: Towards Controlled Geometry of Molecular Chains

Mechanisms for controlling the assembly of molecular arrays in carbon nanotubes via alteration of the size and geometry of the functional groups attached to the molecules inserted into the nanotubes are studied. As model compounds, a series of structurally related fullerenes functionalized with polyaryl groups (C₆₀X, where X is a polyaryl group) of various lengths are synthesized to explore this effect. These molecules are inserted into single‐walled carbon nanotubes (SWNTs) under mild conditions to prevent their decomposition and to form C₆₀X@SNWT structures. The molecular chains thus formed are studied by high‐resolution transmission electron microscopy, X‐ray diffraction, and Raman spectroscopy, revealing that the functional groups increase the interfullerene separation proportionally with the size of X. However, the functional groups themselves appear to adopt various orientations with respect to each other and exhibit intermolecular π–π interactions within the cavities of the carbon nanotubes. All these effects create a distribution of observed interfullerene separations in nanotubes, which are examined by theoretical simulations and interpreted in terms of molecular geometries and intermolecular interactions.     

Extraction of Exotic Fullerenes and Purification of Single-Walled Nanotubes

In this report, we presented a novel and simple extraction method, namely Hydrothermally Initiated Dynamic Extraction (HIDE) method, which allows the extraction of exotic fullerenes remaining in the fullerene soot. In the HIDE method, the soot was treated in boiling water that neither dissolved fullerenes nor produced minimal by-products but untangles the fullerenes from the soot, prior to the extraction by organic solvent. As a result, the HIDE method allowed the extraction of exotic fullerenes, such as dimeric fullerene oxides, higher fullerenes having a low symmetry and oxidized higher fullerenes. Accordingly, the single walled nanotubes (SWNTs) with a purity of 99% by wt was achieved for the first time with the application of the HIDE method.