2009 Vol. 24, No. 04

Structural characteristics of endohedral metalofullerenes ranging from C66 to C84
XU Bing-she, ZHANG Zhu-xia, LIU Guang-huan, LIU Xu-guang
2009, 24(04): 289-300. doi: 10.1016/S1872-5805(08)60052-9
Abstract(1868) PDF(1678)
Abstract:
As the size of the fullerene cage increases, the possibility for the existence of multiple isomers also increases. Most fullerenes and endohedral fullerenes obey the isolated pentagon rule (IPR), which requires that each of the twelve pentagons in the carbon cage be surrounded by hexagons. Non-IPR structures have already been isolated for cages containing 66,68, 70, 72, 74,78 or 84 carbon atoms. The structural characteristics of the endohedral metallofullerenes, which consist of carbon cages from C66 to C84 and encaged species including one, two, three atoms, metal nitrides(M3N) or metal carbides(M2C2) are illustrated.
Attachment of biomolecules (protein and DNA) to amino-functionalized carbon nanotubes
Kalpana Awasthi, D.P. Singh, Sunil Singh, D. Dash, O.N. Srivastava
2009, 24(04): 301-306. doi: 10.1016/S1872-5805(08)60053-0
Abstract(1878) PDF(1987)
Abstract:
An efficient method for the attachment of biomolecules [e.g. bovine serum albumin (BSA) protein and deoxyribonucleic acid (DNA)] to amino-group-functionalized multiwalled carbon nanotubes (f-MWCNTs) was reported. MWCNTs were prepared by spray pyrolysis of a benzene-ferrocene solution in argon atmosphere at ~850°C followed by functionalization with an amino group by chemical modification of carboxylic groups introduced on the nanotube surface. This process involves a direct coupling of ethylenediamine with carboxylic groups to introduce amino groups by amide formation. The as-synthesized MWCNTs, f-MWCNTs, and amino f- MWCNTs with BSA protein and DNA were characterized by scanning and transmission electron microscopy, and Fourier transform infrared spectroscopy, which confirm the attachment of biomolecules (BSA protein and DNA) to the amino f-MWCNTs.
Growth of carbon nanotubes by the catalytic decomposition of methane over Fe-Mo/Al2O3 catalyst: effect of temperature on tube structure
SONG Jin-ling, WANG Li, FENG Shou-ai, ZHAO Jiang-hong, ZHU Zhen-ping
2009, 24(04): 307-313. doi: 10.1016/S1872-5805(08)60054-2
Abstract(2959) PDF(1576)
Abstract:
The effects of temperature, reaction time, and flow rate on the structure of carbon nanotubes (CNTs) were studied using catalytic chemical vapor deposition of methane over an Fe-Mo/Al2O3 catalyst. Results show that the temperature is a key parameter to control the wall thickness of the CNTs. Low temperature leads to the formation of multiwalled carbon nanotubes (MWCNTs) with wall thickness of 2–7 nm. Relatively high temperature is in favor of the growth of double-walled carbon nanotubes (DWCNTs), whereas high temperature promotes the generation of single-walled carbon nanotubes (SWCNTs). A further increase of temperature results in the generation of MWCNTs with a wall thickness of 3–15 nm and large carbon particles.
Poly(vinylidene chloride)based carbon as an electrode material for high power electric double layer capacitors
SHI Zhi-qiang, QIAN Qing-li, WANG Cheng-yang, ZHANG Shu-feng, YUAN Guo-qing
2009, 24(04): 314-320.
Abstract(2018) PDF(1271)
Abstract:
A series of poly vinylidene chloride (PVDC) based activated carbons was prepared by carbonization at 600-1100℃. Their formation , crystallinity, surface area and pore structure were characterized by thermogravimetry, X-ray diffraction and nitrogen adsorption. The electrochemical performance was investigated by cycle voltammetry, AC impedance and galvanostatic charge/discharge in a 30 wt. % KOH electrolyte. Results showed that the structure of PVDC-based carbons was amorphous and their high surface area (874-969 m2/g) and abundant micropores were formed during the solid phase carbonization. PVDC-based carbon had a high gravimetric capacitance and specific capacitance per surface area, owing to its optimum pore size distribution suitable for the formation of electric double layers. The PVDC-based carbon heat-treated at 900℃ had a maximum capacitance and an excellent power performance. The specific capacitance can reach as high as 256.9F/g at low discharge current density (50mA/g) and the capacitance retention ratio is 76.5% at high current density (5 000mA/g). The electrical conductivity of PVDC-based carbon increased and the diffusion resistance of electrolyte ions in pores decreased with increasing carbonization temperature, and the rate performance of the electric double layer capacitor is improved as a result
Effect of heating conditions on pore structure and performance of carbon foams
WANG Yong-gang, MIN Zhen-hua, CAO Min, XU De-ping
2009, 24(04): 321-326. doi: 10.1016/S1872-5805(08)60055-4
Abstract(1893) PDF(1565)
Abstract:
Carbon foams were prepared from AR pitch in a high pressure/high temperature reactor under different heating conditions. Their pore structure, bulk density, porosity, compressive strength, thermal conductivity, and crystallite size parameters were measured. Foams produced using a long time at a constant foaming temperature exhibit bigger pore size (412 nm), higher porosity (83.82%), lower bulk density (0.34 g/cm3), higher compressive strength (4.92 MPa), and more interconnected pores than that produced in a short time at the same constant foaming temperature, which exhibit high thermal conductivity (71.34 W/(m·K)) and low interlayer d-spacing (d002) (0.335 56 nm) after graphitization at 2 800°C. The specific thermal conductivity of graphite foams can reach 210 (W·(m·K)-1) /( g·cm-3), which is about five times greater than copper and four times greater than aluminum.
Carbon paper/graphite composite loaded with NiHCF thin film for alkaline ion separation
MA Xu-li| HAO Xiao-gang| LI Yong-guo| YANG Yan-yan| LIU Shi-bin| SUN Yan-ping
2009, 24(04): 327-332.
Abstract(1915) PDF(1406)
Abstract:
Nickel hexacyanoferrate (NiHCF) thin films were loaded within the porous channels of a carbon paper/graphite electrode by capillary chemical deposition. The composite film electrode was investigated for electrochemically controlled ion separation in an alkaline cation solution. The morphology and composition of the composite film electrode were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, infrared spectroscopy and X-ray photoelectron spectroscopy. Cyclic voltammetry was used to investigate the separation capacity, cycle life and regeneration ability of NiHCF film electrodes in 1 mol·L-1 KNO3 and CsNO3 solution. Results show that the composite film electrodes had a high ion exchange capacity, low diffusion resistance, good cycling stability and regeneration ability. It is suggested that the composite film electrodes are suitable for the selective separation of alkaline cations.
Potential to use mesoporous carbon as catalyst support for hydrodesulfurization
TAN Zheng-li, XIAO Hui-ning| ZHANG Run-duo, ZHANG Zi-sheng, Serge Kaliaguine
2009, 24(04): 333-343. doi: 10.1016/S1872-5805(08)60056-6
Abstract(2732) PDF(2051)
Abstract:
A range of mesoporous carbons as potential supports to enhance ultra-deep hydrodesulphurization (HDS) of diesel fuel was synthesized using a sol-gel method. SBA-15 was used as template and sucrose and furfuryl alcohol were used as carbon sources.  Various carbon incorporation approaches were used. From the results of nitrogen adsorption, transmission electron microscopy and X-ray diffraction, the synthesized carbon exhibited good replication of the SBA-15 structure. Loading of Co-Mo into the mesoporous carbons and catalysis dispersion were evaluated using various techniques including X-ray photoelectron spectroscopy and energy dispersive X-ray analysis. The intrinsic HDS activity was evaluated by NO chemisorption on the prepared catalysts, which showed that the catalyst supported on mesoporous carbon using sucrose as carbon precursor has a higher NO uptake than that supported on commercial activated carbon.
Surface modification and application of multi-walled carbon nanotubes in fire-retardant coatings
QIU Jun, ZHANG Shi-hong, WANG Guo-jian, GONG Yi-lei
2009, 24(04): 344-348.
Abstract(2185) PDF(1432)
Abstract:
Multi-walled carbon nanotubes (MWCNTs) were modified by grafting an amphiphilic polymer, which were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. The modified MWCNTs were added to an intumescent fire-retardant coating and their effects on the performance of the coating were studied. Results show that the amphiphilic polymer can be attached to the surface of MWCNTs by appropriate processing, and the modified MWCNTs exhibit a remarkable solubility in butyl acetate and distilled water. The modified MWCNTs added to the coating can strengthen the carbonized layers, increase intumescent times and decrease the increasing rate of the rear temperature when the coating was exposed to a fire. The modified MWCNTs can also enhance the crack resistance of the coating.
Carbon matrices with different pore structures as heat transfer intensifier in paraffin wax/carbon thermal energy storage system
2009, 24(04): 349-353.
Abstract(2135) PDF(1616)
Abstract:
Graphite foam, carbon felt and compressed expanded natural graphite (CENG) were used to increase the heat transfer ability of paraffin wax as latent heat storage (LHS) medium. Structure and thermal properties of the paraffin wax-carbon LHS system were characterized using the scanning electron microscopy, laser flash technique and differential scanning calorimetry. Results indicated that the thermal conductivities of paraffin wax-graphite foam, paraffin wax-carbon felt and paraffin wax-CENG systems were enhanced by a factor of 437, 14 and 25 times, respectively, compared with pure paraffin wax and their latent heats were 42.34J/g, 48.38J/g and 57.82J/g respectively.
Growth mechanism of carbon microcoils with changing fiber cross-section shape
CHENG Jing-bao, DU Jin-hong, BAI Shuo
2009, 24(04): 354-358. doi: 10.1016/S1872-5805(08)60057-8
Abstract(2490) PDF(1255)
Abstract:
Carbon microcoils (CMCs) with a fiber cross-section changing from flat to circular along with a coil diameter changing from 4.2 to 6.0 μm, which may develop a novel spring for micromechanical systems, were obtained by controlling the acetylene flow rate using Ni catalyst at a temperature of 1 013-1 053K. A growth model for these changes was proposed in which catalytic anisotropy is considered to be the possible factor changing the fiber cross-sectional shape of the CMCs. Owing to the change of catalytic anisotropy caused by reaction conditions, the same slender catalyst can produce both flat CMCs and circular CMCs depending on its relative orientation to the fiber axis. A cubic Ni catalyst can only produce a circular CMC, and can only change the coil diameter upon changing the reaction conditions. The model will give more insight into the formation of CMCs and provide information on the controlled synthesis of CMCs and carbon fibers.
Modification of a LiFePO4 cathode for lithium ion batteries by carbon coating and copper doping
GUAN Yi-biao, WU Feng, BAI Ying, WU Chuan
2009, 24(04): 359-363.
Abstract(1894) PDF(1507)
Abstract:
The effects of a carbon coating and copper doping on the electrochemical performance and tap density of a LiFePO4 cathode for lithium ion batteries were investigated by XRD, SEM, charge/discharge cycle tests, rate tests and tap density tests. Results showed that the average discharge capacity of LiFePO4/C and LiFe0.95Cu0.05PO4 were 147mAh/g and 131mAh/g respectively. The capacity fading rate of LiFe0.95Cu0.05PO4 was much larger than that of LiFePO4/C in a high-rate discharging test. The electrochemical performance of LiFePO4/C was better than that of LiFe0.95Cu0.05PO4, but the tap density of the latter was 1.5 times as large as that of the former.
Effect of graphitization on the kinetics and mechanism of thermal oxidation of carbon microcoils
BI Hui| KOU Kai-chang| WANG Zhao-di, WANG Zhi-chao, ZHANG Jiao-qiang
2009, 24(04): 364-368.
Abstract(2161) PDF(1317)
Abstract:
Carbon microcoils were prepared by catalytic chemical vapor deposition, using acetylene as carbon source, Ni powder as catalyst, and a sulfur-containing compound (thiophene) as growth promoter. The microcoils were graphitized under an argon atmosphere at 2 500 °C. The morphology and microstructure of the oxidized carbon microcoils were investigated by scanning electron microscopy, and their oxidation resistance was studied by thermogravimetric analysis. Results reveal that oxidation resistance of the carbon microcoils is improved through graphitization, and the graphitized carbon microcoils retain their microcoil morphology after oxidation. Oxidation is a first order reaction and the activation energies are 263 and 297 kJ/mol before and after graphitization, respectively.
Chemical functionalization of multiwalled carbon nanotubes by hexamethylene diamine
ZHANG Fu-hua, WANG Rong-guo, HE Xiao-dong, LIU Wen-bo, You Jie
2009, 24(04): 369-374.
Abstract(2635) PDF(1328)
Abstract:
Multiwalled carbon nanotubes (MWCNTs) were modified by grafting with hexamethylene diamine to obtain reactive amine groups. Acid treatment was used to shorten the MWCNTs by cutting at defect sites. Carboxyl groups produced by the acid treatment were converted to carbonyl chloride by thionyl chloride, and hexamethylene diamine was grafted to the ends of the cut MWCNTs by its substitutional reaction with carbonyl chloride. XPS, TEM and SEM were used to characterize the samples during the course of modification. Results indicated that MWCNTs were shortened from tens of microns to about 500 nm by the acid treatment. Hexamethylene diamine was successfully grafted onto the ends of the MWCNTs with a grafted N content as high as 3.29 mol %. The grafted MWCNTs can be dispersed uniformly in acetone.
A simple solvothermal route to synthesize carbon microspheres
MI Yuan-zhu, LIU Ying-liang
2009, 24(04): 375-378. doi: 10.1016/S1872-5805(08)60058-X
Abstract(1914) PDF(1313)
Abstract:
Carbon micro-spheres were prepared by a simple solvothermal route in a stainless steel autoclave. Absolute ethanol was used as carbon source and solvent, and nickel as catalyst, obtained by reducing Ni(Ac)2 in absolute ethanol. Carbon microspheres were obtained at 500 °C for 48h. The samples were characterized by X-ray powder diffractometer, scanning and transmission electron microscopy, and Raman spectroscopy. Results showed that there were acicular and spherical carbon particles in the as-prepared samples. The carbon microspheres had diameters ranging from 1 to 2 μm. and the acicular particles had diameters ranging from 1 to 2 μm and lengths ranging from 3 to 6 μm. The yield of carbon micro-spheres was over 95% with a narrow size distribution and perfect shape.
Preparation of nitrate-H2SO4-graphite intercalation compounds by a two-step intercalation method
HAN Zhi-dong, DU Peng, DONG Li-min, ZHANG Xian-you
2009, 24(04): 379-382.
Abstract(1907) PDF(1361)
Abstract:
Ternary graphite intercalation compounds (GICs), nitrate/nitric acid-sulfuric acid-GICs, were prepared by a two-step method. Their structure was characterized by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Results showed that the two-step method favored the formation of lower stage-GICs by promoting the intercalation of nitrate or nitric acid and enlarging the interlayer spacing. The expanded GICs, whose expansion volume can reach 450mL/g, showed obvious graphite layers and a uniform porous structure. The two-step method had many advantages compared with the direct intercalation method, such as safety in operation, less pollution during experiments and ease of industrial scale-up.
Professor Maozhang Wang and his research activities in carbon materials
YANG Yong-gang| YANG Quan-hong
2009, 24(04): 383-384.
Abstract(2026) PDF(1284)
Abstract:
Prof. Maozhang Wang was born in October 1938, and graduated from Tianjin University in 1960. Since then, he has been working on carbon- and coal -related research programs in the Institute of Coal Chemistry, Chinese Academy of Sciences. In the early 1980’s, he spent two years doing research on liquid-phase carbonization chemistry in Kyushu University, Japan. As one of the organizers, he was involved in many social activities in the Chinese Carbon Society and he was a member of the advisory and editorial boards of several Chinese carbon journals. In his nearly 50 years’ research on carbon, his research activities span from carbon fibers and activated carbon fibers to very novel carbon materials such as carbon nanotubes and graphene. He worked as the principal or main investigator for many projects on carbon. He also wrote a lot of review papers and books to introduce the latest advances on novel carbon materials. Two of the books, “Carbon fibers and their composites” and “Preparation, properties and applications of carbon fibers” were regarded as basic carbon textbooks by many carbon researchers in China.