共查询到20条相似文献,搜索用时 46 毫秒
1.
Franco Cataldo 《Fullerenes, Nanotubes and Carbon Nanostructures》2005,13(1):31-41
The effect of the electric arc between graphite electrodes submerged in n-hexane solutions of C60 fullerene has been studied by electronic absorption spectroscopy, liquid chromatographic analysis (HPLC-DAD), and FT-IR spectroscopy. The experimental results show that C60 does not appear able to inhibit the polyynes' formation at the concentration used. Polyynes are formed in large amounts as usual from the graphite arc, and polycyclic aromatic hydrocarbons have been detected as by-products. Prolonged arcing causes the disappearance of C60 from the solution. There is experimental evidence that C60 undergoes radical addition reactions during the early stages of arcing. 相似文献
2.
设计了化学物质对真空电子吸收效果评价的密度泛函理论(DFT)评价法和气相色谱-电子捕获检测器(GC-ECD)评价法,并利用两种方法对CCl2H2、CCl3H和CCl4三种氯代甲烷的电子吸收效果进行了评价,并对两种方法的结果进行了对比分析。DFT评价法表明,从结构上三种氯代甲烷均表现出明显的电子吸收潜力,且CCl2H2、CCl3H和CCl4得电子潜力依次增强;GC-ECD评价法表明,CCl2H2、CCl3H和CCl4在ECD检测器上均具有较好的响应,且CCl4响应最强,CCl2H2最弱。综合考虑DFT评价结果和GC-ECD评价结果,三种氯代甲烷均具有优越的电子捕获能力,且CCl4捕获电子能力最强,CCl3H次之,CCl2H2最弱;同时也说明,氯代甲烷可以作为电离层扰动物质的备选物质。 相似文献
3.
《Fullerenes, Nanotubes and Carbon Nanostructures》2007,15(4):291-301
The carbon arc in liquid argon in presence of methane produces the complete series of polyynes from C4H2 to C12H2 which have been collected in a cold trap and analyzed by electronic absorption spectroscopy and by liquid chromatography (HPLC-diode array). The relative abundance of the polyynes series has been determined. In addition to polyynes the decomposition of methane in the argon arc produces also vinylacetylene and naphthalene. Thermodynamic calculations explain why the polyynes are formed so easily in the carbon arc. 相似文献
4.
Franco Cataldo 《Fullerenes, Nanotubes and Carbon Nanostructures》2004,12(3):633-646
Since polyynes are easily accessible with the submerged electric arc synthesis between graphite electrodes, the chemical behavior of polyynes solutions in different solvents has been explored. It has been found that surprisingly the polyynes solutions, with polyynes having up to 16 carbon atoms arranged in a chain, are stable in air over 1 week time in the dark. These solutions react relatively slowly with ozone while add rapidly and completely bromine. The polyynes solutions are instead quite easily photolyzed under the action of UV radiation both in air and under N2. Two different light sources were used in the study: a low pressure mercury lamp emitting almost a monochromatic radiation at 254 nm and an high pressure mercury lamp emitting in a broad wavelength range in the ultraviolet. With the former monochromatic light source, it has been demonstrated the possibility to perform a selective photolysis of selected polyynes in a mixture of homologous series. 相似文献
5.
Franco Cataldo 《Fullerenes, Nanotubes and Carbon Nanostructures》2005,13(1):21-30
The main products of the submerged electric arc between graphite electrodes in n-hexane and in methanol are the polyynes series. The liquid chromatographic analysis (HPLC) of the arcing products in n-hexane reveals also the presence of a mixture of polycyclic aromatic hydrocarbons (PAHs) as minor products. Naphthalene, acenaphthylene, phenanthrene, perylene, fluoranthene, benzo[b]fluoranthene, pyrene, and the related compound cyclopenta[c,d]pyrene have been identified. Even crysene and acenaphthene were reasonably identified from the PAHs mixture. The PAHs mixture appears to derive essentially from the plasmalysis of the solvent where the electric arc is conducted, while the polyynes are formed from the elemental carbon supplied from the graphite electrodes. Another minor product is represented in all cases by the formation of carbon black or carbon coke, which appears more abundant in n-hexane rather than in methanol. The different results are explained thermodynamically in terms of different carbonization tendency of the solvents used. 相似文献
6.
Zden k Slanina Filip Uhlí k Long Y. Chiang Ludwik Adamowicz 《Fullerenes, Nanotubes and Carbon Nanostructures》2002,10(4):363-372
Quantum-chemical computations are reported for hexa-sulfobutyl fullerenes C60((CH2)4SO3H)6 (FC4S). FC4S represent novel water-soluble fullerene derivatives with an enhanced radical scavenging activity and also possible potential for materials science. The computations have been carried out with the standard version of the PM3 semiempirical quantum-chemical method. It is found out that the lowest among the computed eight FC4S species has the structural pattern already observed for C60Cl6. However, a larger-scale search is at present prevented by the demands on computational resources. 相似文献
7.
SiC and TiC coatings were deposited by CVD on graphite substrates and the effect of the variation of the methane (CH4) and hydrogen (H2) ratio on deposition was investigated. SiCl4, TiCl4 and CH4 were used as sources of Si, Ti and C. In case of the SiC coatings, stoichiometric SiC was obtained when the ratios of CH4/(SiCl4 + CH4)andH2/(SiCl4 + CH4) are 0.4 and 10, respectively. Stoichiometric TiC was also obtained under similar conditions. In order to obtain non-stoichiometric materials for possible fabrication of functionally gradient materials (FGM), a change of microstructure and composition was observed with changes of the CH4 and H2 ratio. As a result, SiC, TiC and C contents were more easily controlled by a change of the H2 ratio compared to the CH4 ratio for SiC and TiC deposition. It has been verified that the change of the H2 ratio is more desirable for possible manufacturing of SiC/TiC/C FGM. 相似文献
8.
Miao Wang Xinluo Zhao Masato Ohkohchi Yoshinori Ando 《Fullerenes, Nanotubes and Carbon Nanostructures》1996,4(5):1027-1039
Carbon nanotubes prepared by de arc discharge of graphite electrodes in He and CH4 gas took markedly different morphology. Thick nanotubes embellished with many carbon nanoparticles were obtained by evaporation under high CH4 gas pressure and high arc current. Thin and long carbon nanotubes were obtained under a CH4 gas pressure of 50Torr and an arc current of 20A for the anode with a diameter of 6mm. 相似文献
9.
Masao Shibuya Motoshi Kato Masaki Ozawa P. H. Fang Eiji ૿ sawa 《Fullerenes, Nanotubes and Carbon Nanostructures》1999,7(2):181-193
It was confirmed that soot produced by free burning of small hydrocarbons like benzene and cyclohexane generally contains less than 0.1 ppm of C60. Small, but measurable amounts of C60 were found in two samples of charcoal, providing the first indication of fullerene formation in the solid state. 相似文献
10.
The kinetics of electrode reaction was investigated by cyclic voltammetry, and cyclic voltammograms show that the reversibility of the Fe(bpy)32+/Fe(bpy)33+ electrode reaction is better than that of the Zn/Zn2+ electrode reaction on the graphite disc. However, the Fe(bpy)32+ ion diffusion in electrolyte is subject to greater resistance than that of the Zn2+ ion one. The stability of the Fe(bpy)3Cl2 solution was investigated by UV–vis spectroscopy, and the performance of a mild redox flow battery employing ZnCl2 and Fe(bpy)3Cl2 in the NaCl aqueous solution with various membranes as the separator was also investigated. It was found that the Celgard 3501 membrane cannot effectively prevent Fe(bpy)32+ ions from leaking into anolyte, leading to the rapid failure of the flow battery. Although the Nafion 115 membrane can be polluted by Fe(bpy)32+ ions, it is not invalidated. The Nafion 115 membrane shows good selectivity, which can avoid Fe(bpy)32+ ions from leakage into anolyte. The ZnCl2/Fe(bpy)3Cl2 flow battery with the Nafion 115 membrane exhibits the capacity retention of 80% after 200 cycles. 相似文献
11.
《Fullerenes, Nanotubes and Carbon Nanostructures》2007,15(3):155-166
The storage stability of an acetonitrile solution of polyynes and monocyanopolyynes was studied by liquid chromatographic analysis for about 50 days at room temperature in a closed Pyrex flask. Monocyanopolyynes decomposition starts immediately after their synthesis; the decomposition can be approximated by a pseudo-first-order kinetic law and the rate constant is dependent from the length of the monocyanopolyyne chains, being faster for longer chains. For instance, for HC7N the decomposition rate is k=-3.4×10-7 s-1 but becomes -7.0×10-5 s-1 for HC13N decay, 204 times faster than the decay of the former compound. Polyynes mixed with monocyanopolyynes in the same CH3CN show an induction time before starting to decompose. The induction time appears linked to the decomposition of monocyanopolyynes, which seems to protect the polyynes from the decomposition. Once the monocyanopolyynes are vanished also the decomposition of polyynes starts with a slower kinetics than monocyanopolyynes and following the rule that longer chains disappear at higher speed than shorter chains. For example, the pseudo-first-order rate constant for C8H2 is k=-1.31×10-8 s-1. Ammonia exerts a deleterious effect on monocyanopolyynes. In fact, ammonia addition to an acetonitrile solution of monocyanopolyynes causes their immediate decomposition due to a nucleophilic addition of ammonia to the polyyne chains. Instead, hydrogen-teminated polyynes are much more resistant toward the nucleophilic addition of ammonia. Hydrochloric acid does not influence the stability of polyynes and monocyanopolyynes. 相似文献
12.
M. Terrones W. K. Hsu S. Ramos R. Castillo H. Terrenes 《Fullerenes, Nanotubes and Carbon Nanostructures》1998,6(5):787-800
Novel graphitic nanostructures (e.g. nanotubes, graphitic onions, polyhedral particles, hemitoroidal nanotube caps and branched nanotubes) are produced by arcing graphite electrodes, containing hexagonal-BN, in inert atmospheres. The introduction of BN or B inside the graphite anode generates long (≤ 20μm) and well graphitised carbon nanotubes exhibiting boron at their tips. High Resolution Electron Microscopy (HRTEM), Scaning Electron Microscopy (SEM), Electron Energy Loss Spectroscopy (EELS) and X-ray powder diffraction studies reveal the production of B4C crsytals, in addition to little amounts of BC3 nanotubes. Mass spectrometry (MS) studies over the generated soots indicate high yields of large fullerenes (e.g. C70, C76, and C84) and thermo-Gravimetric analysis (TGA) of the nanostructures show high oxidation resistance. 相似文献
13.
P. A. Troshin O. Popkov R. N. Lyubovskaya 《Fullerenes, Nanotubes and Carbon Nanostructures》2003,11(2):165-185
The effect of the reagent ratio, reaction time and power of the reagent on the product composition in chlorination of [60]fullerene was studied. Chlorofullerenes C60Cl6, C60Cl8, C60Cl10, C60Cl12, C60Cl14, and C60Cl26 were synthesized and characterized by chemical analysis, FTIR, 13C NMR, and MALDI TOF mass spectrometry. The experimental data supported the coexistence of several isomers of C60Cln (n = 8, 10, 12, 14, 26); the mixtures were not separated so far. Semiempirical calculations (AM1, PM3) were used to analyze the addition patterns and resulted in the most favorable structures of C60Cl8-26. Chlorination of C70 under various conditions invariably yielded C70Cl10. 相似文献
14.
C60 was treated at room temperature, in air with intense ultrasound in the following solvents; decalin, tetralin. cyclohexane and CCl4. It is shown by UV-VIS and FT-IR spectroscopy that in decalin and in tetralin the dominant reaction seems to be a sono-oxidation, although more complex reactions involving the solvent take place. In CC14 sono-oxidation is accompanied by an extensive sono-polymerization. Products in CCl4 are C60O, C60O2 and others; the sonopolymer collected from sonicated CCl4 was easily identified by FT-IR spectroscopy. Sonopolymerization occurs also in decalin and tetralin and is promoted by free radicals as in the case of CCl4. No reactions are observed in cyclohexane due to the very low solubility of C60 in this solvent and the poor cavitation ability of cyclohexane under the action of ultrasound. 相似文献
15.
Toshiyuki Oyama Tadahiro Ishii Kazuo Takeuchi 《Fullerenes, Nanotubes and Carbon Nanostructures》2000,8(6):491-499
Endohedral lanthanum fullerenes, La@C60, La@C82 and La2C80, were synthesized by ablation of graphite and La2O3 in flowing Ar buffer gas with a 1064 nm beam from a pulsed-Nd: YAG laser in which the graphite was heated by the CW-Nd:YAG laser up to 2500 °C. The La-fullerenes were also prepared by laser ablation of a lanthanum-graphite composite rod. The extractant fullerenes from the carbon soot were analyzed by laser-desorption time of flight mass spectrometry (LD-TOF MS). The relative yield of La@C82, increased with increasing temperature of the rod in the range of 700-2300 °C. 相似文献
16.
Adrian J. Adamson John H. Holloway Eric G. Hope Roger Taylor 《Fullerenes, Nanotubes and Carbon Nanostructures》1997,5(4):629-642
U.V. irradiation of a solution of [60]fullerene in carbon tetrachloride saturated with chlorine gave a yellow solid, the negative ion FAB mass spectrum of which is consistent with the presence of C60Cl24 When a solution of [60]fullerene in CCl4was mixed with IF5, a yellow solid was deposited in the denser IF5 layer. The negative ion FAB mass spectrum of this material indicated it to be C60C18F14 This result provides the first confirmation that halogenation of Merenes is a radical process. Fluorination of C60Br8 gave a range of fluorinated products, having a maximum fluorine content of ca. 36 fluorines per cage, and with either C60F18 or its mono-oxide as major species. EI mass spectrometry of the products at various temperatures indicates that the more highly fluorinated fiiilerenes are either less stable to heat, or are more volatile. 相似文献
17.
M. Manciu R. Manaila A. Devenyi T. Braun 《Fullerenes, Nanotubes and Carbon Nanostructures》1994,2(3):255-289
The structure of pollycrystalline C60 films prepared by sublimation from 99.9% pure C60 powder and from graphite soot was investigated by X-ray diffraction. A complex fcc (111) line was found in the former samples. Comparison of experimental and simulated (111) profiles allowed to assess quantitatively the degree of stacking disorder introduced during the growth of the film. Probabilities could be derived for continuation of already started fcc and hep sequences, thereby characterizing the statistical microstructure of the C60 films. Also, the relative magnitudes of inter- and intra-layer disorder can be estimated. The films deposited from graphite soot show a high structural disorder. 相似文献
18.
N. N. Belov S. K. Simanchev A. V. Tokarevskikh 《Fullerenes, Nanotubes and Carbon Nanostructures》1997,5(7):1449-1460
The cathode slag structure and the graphite anode surface have been investigated. Dependence of geometrical parameters of the slag from the time has been found. Efficiency of C60 generation was increased with arcing time. Use of cathode with closed hole reduced the yield of C60 相似文献
19.
以硝酸铋、氯化钠和氢氧化钠为原料用液相沉淀法制备g-C3N4/Bi12O17Cl2复合光催化剂,并用X射线衍射(XRD)、傅里叶红外光谱(FT-IR)、扫描电子显微镜(SEM)、紫外-可见漫反射光谱(UV-Vis DRS)等手段表征其组成、微观形貌和性能,以罗丹明B为模拟污染物研究了在可见光照射下g-C3N4对g-C3N4/Bi12O17Cl2复合光催化剂活性的影响及其光催化机理。结果表明,2% (质量分数) g-C3N4/Bi12O17Cl2复合光催化剂的光催化性能最好,见光90 min后对罗丹明B的降解率达到98%。 相似文献
20.
Franco Cataldo 《Fullerenes, Nanotubes and Carbon Nanostructures》2002,10(4):293-311
The thermal behavior of graphite, C60 fullerene, fullerene black (carbon soot containing fullerenes), extracted fullerene black and diamond has been analyzed to 1000°C by TGA-DTA (thermogravimetric analysis and differential thermal analysis) under a nitrogen flow at a heating rate of 20°C/min. Very small weight losses have been recorded in the case of graphite and diamond. Furthermore no diamond graphitization has been observed. The sublimation of pure C60 and the fullerene fraction of fullerene black (both pristine and extracted) has been observed and discussed.
The combustion reaction in air flow of graphite, C60 and C70 fullerenes, fullerene black (both unextracted and extracted), carbon nanotubes and diamond has been studied by TGA-DTA at a heating rate of 20°C/min. C70 fullerene and fullerene black have been found to be the most reactive carbon materials with O2. The role played by C70 in the degradation of fullerites has been discussed. Among the carbon materials examined, the best resistance to O2 attack has been shown by diamond and carbon nanotubes. The behavior of graphite is intermediate between diamond and fullerene blacks. The behavior of C60 fullerene appears closer to that of graphite although it appears to be more reactive with O2. Samples of graphite and carbon blacks N375 and N234 have been studied by TGA-DTA in air flow before and after a radiation treatment with neutrons or γ radiation. The effect of the radiation damage in the combustion reaction of these carbon materials has been discussed. 相似文献
The combustion reaction in air flow of graphite, C60 and C70 fullerenes, fullerene black (both unextracted and extracted), carbon nanotubes and diamond has been studied by TGA-DTA at a heating rate of 20°C/min. C70 fullerene and fullerene black have been found to be the most reactive carbon materials with O2. The role played by C70 in the degradation of fullerites has been discussed. Among the carbon materials examined, the best resistance to O2 attack has been shown by diamond and carbon nanotubes. The behavior of graphite is intermediate between diamond and fullerene blacks. The behavior of C60 fullerene appears closer to that of graphite although it appears to be more reactive with O2. Samples of graphite and carbon blacks N375 and N234 have been studied by TGA-DTA in air flow before and after a radiation treatment with neutrons or γ radiation. The effect of the radiation damage in the combustion reaction of these carbon materials has been discussed. 相似文献