2013 Vol. 28, No. 1

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Effect of multi-walled carbon nanotubes on the thermal stability and surface morphology of LiFePO4 cathode material
Mária Filkusová1, 　Andrea Fedorková2, 3, 　Renáta Oriňáková2, Andrej Oriňák2
2013, 28(1): 1-7.
Abstract(1518) PDF(1276)
Abstract:
A novel network composite cathode was prepared by mixing LiFePO4 particles with multiwalled carbon nanotubes (MWCNTs). LiFePO4 particles were connected by MWCNTs and a polymer binder, polypyrrole-polyethylene glycol (PPy-PEG), to form a three-dimensional network. The surface morphology and thermal stability of the LiFePO4-MWCNT/PPy-PEG composite cathode were investigated by scanning electron microscopy, thermogravimetric analysis and pyrolysis capillary gas chromatography. It was found by scanning electron microscopy that the particle size of LiFePO4 in the LiFePO4-MWCNT sample was smaller than that of the pure LiFePO4 and the structure in the LiFePO4-MWCNT/PPy-PEG sample was more homogeneous than in the LiFePO4-MWCNT/PPy sample. Thermogravimetric analysis indicated that PPy-PEG blend polymer in combination with MWCNTs considerably improves the thermal stability of the final cathode material. Pyrolysis capillary gas chromatography measurements at 500℃ showed a decreased thermal stability of organic species contained in the composite cathode material. The addition of MWCNTs was an effective way to increase homogeneity and thermal stability of the LiFePO4-MWCNT/PPy-PEG cathode material.
Synthesis of coaxial nanocables of single-walled carbon nanotubes sheathed with amorphous silicon oxide
ZHANG Yan-li
2013, 28(1): 8-13.
Abstract(1307) PDF(1346)
Abstract:
Coaxial nanocables of single-walled carbon nanotubes (SWCNTs) sheathed with amorphous silicon oxide were directly synthesized by a hydrogen arc discharge method. As-prepared nanocables are usually tens of microns in length and about 10-30nm in diameter. The sheath of the nanocables is amorphous silicon oxide, while the core is high quality SWCNTs. Each cylinder-shaped nanocable contained one to several SWCNTs. The growth mechanism of the nanocables is proposed. These SWCNT/amorphous silicon oxide nanocables may have potential applications in field effect transistors and other related nanodevices.
Modification of carbon nanotubes with sodium p-aminobenzenesulfonate and its effect on Cu2+ adsorption
ZHENG Jing-zhi1
2013, 28(1): 14-19.
Abstract(1362) PDF(1167)
Abstract:
Multiwalled carbon nanotubes (MWCNTs) were oxidized by concentrate HNO3 and then reacted with SOCl2 to form MWCNT-COCl. Water-soluble sodium p-aminobenzenesulfonate-grafted multiwalled carbon nanotubes (MWCNT-CO-NHC6H5SO3Na) were synthesized by an amidation reaction of sodium p-aminobenzenesulfonate with MWCNT-COCl, which was verified by FT-IR spectroscopy. The content of the sodium p-aminobenzenesulfonate grafted onto the MWCNT surface reached 29.9 mass%. The MWCNT-CO-NHC6H5SO3Na showed a good solubility and dispersion in water, and had an improved adsorptive performance for the removal of low concentrations of Cu2+ in water. The adsorption isotherms of the MWCNT-CO-NHC6H5SO3Na for Cu2+ can be well fitted by the Freundlich equation.
Effect of magnetic field treatment on the electrical conductivity of low-density polyethylene and its composites with CNTs
HAN Bao-zhong, 　MA Feng-lian, 　GUO Wen-min, 　WANG Yan-jie, 　JIANG Hui
2013, 28(1): 20-25.
Abstract(1228) PDF(1237)
Abstract:
Low-density polyethylene (LDPE) and carbon nanotube (CNT) composites (CNT/LDPE) were treated during their hot-press molding using a strong static magnetic field. The effect of the magnetic field on the direct current electrical conductivity of these materials was investigated and the mechanism for the effect was analyzed by differential scanning calorimetry, polarized light microscopy and atomic force microscopy. Results indicate that the magnetic field treatment increases the degree of crystallization and the volume resistivity of the composites. The induced magnetic moment in the CNTs caused by the magnetic field leads to an improved orientation of the CNTs in LDPE along the magnetic field direction during molding, which causes an increase in the electrical conductivity of the CNT/LDPE composites in the magnetic field direction and an increase of nonlinear conductivity characteristics. The increased amplitude of electrical conductivity of the composites increases with the increasing amount of CNTs added.
Electrocatalytic oxidation of ascorbic acid on carbon nanotube/cubic nickel cyanoferrate/polyaniline hybrid films
MA Xu-li
2013, 28(1): 26-32.
Abstract(1490) PDF(1158)
Abstract:
Carbon nanotube/cubic nickel cyanoferrate/polyaniline hybrid films were synthesized by cyclic voltammetric electrodeposition of NiSO4, K3Fe(CN)6 and aniline in a H2SO4/Na2SO4 solution on a platinum electrode coated with carbon nanotubes. The electrocatalytic oxidation performance for ascorbic acid (AA) using the hybrid film as an electrode was investigated by cyclic voltammetry and chronoamperometry. The morphology of the film was investigated by scanning electron microscopy. The hybrid film was used for AA detection, and showed a high electrocatalytic activity, a high sensitivity and a low detection limit. The linear range for the detection of AA was from 1×10-5 to 1.4×10-4mol/L with a correlation coefficient of 0.9966, a sensitivity of 654mA·M-1·cm-2 and a detection limit of 6.09×10-6mol/L. The diffusion coefficient and the catalytic rate constant of the electrocatalytic oxidation of AA were studied by chronoamperometry.
Preparation of aligned carbon nanotubes by water vapor-assisted CVD
LIU Ting-zhi1, 　LIU Yong3
2013, 28(1): 33-38.
Abstract(1369) PDF(1218)
Abstract:
Water vapor-assisted chemical vapor deposition was used to prepare vertically-aligned carbon nanotubes (ANTs) on a quartz substrate by using ferrocene as a catalyst precursor and xylene as a carbon source. The morphologies of the ANTs were investigated by TEM and SEM. Results showed that under optimized growth conditions ANTs were grown on the substrate with an area of 60×140 mm2 and a thickness of 2.05 mm. The ANTs emit strong white light under microwave radiation, indicating that they are a potential microwave absorption material.
Gas separation performance of carbon materials produced from phenolic resin: Effects of carbonization temperature and ozone post treatment
Mohammad Mahdyarfar1, 2, 　Toraj Mohammadi2, 　Ali Mohajeri1
2013, 28(1): 39-46.
Abstract(1444) PDF(915)
Abstract:
The effect of carbonization temperature and treatment with ozone on the porosity and gas separation behavior of carbons produced from phenolic resin was investigated. Results showed that with increasing carbonization temperature from 500 to 800℃, the average pore diameter decreased, while the pore volume and the adsorption capacity of the carbons first increased and then decreased A molecular sieve separation mechanism was also observed for the sample carbonized at 800℃. The pore size increased and the adsorption capacity and the kinetic adsorption selectivity for oxygen/nitrogen were decreased by the ozone treatment.
Preparation of TiO2/mesoporous carbon composites and their photocatalytic performance for methyl orange degradation
YIN Bo1, 　WANG Ji-tong1
2013, 28(1): 47-54.
Abstract(1378) PDF(1391)
Abstract:
Mesoporous carbon (MC) prepared using colloidal silica templates was used as a support to synthesize TiO2/MC composites using a sol-gel method. The TiO2 content and the crystalline structure of TiO2/MC photocatalysts can be tuned by the precursor composition and calcination temperature, respectively. MC and TiO2/MC composites were characterized by nitrogen adsorption, XRD, TG, SEM, TEM and electron energy dispersive spectroscopy. Results showed that the anatase TiO2 nanoparticles were highly dispersed on the surface of the carbon framework. As-prepared composites exhibited high photocatalytic activities for methyl orange (MO) degradation under UV irradiation, and a synergistic effect of adsorption and photocatalytic degradation was observed. The MO removal rate reached 89% after UV irradiation for 75 min. The kinetics of MO degradation can be well fitted with a first-order reaction model and the largest rate constant observed was 0.015 min-1.
Preparation of nanoporous carbons with hierarchical pore structure for CO2 capture
TANG Zhi-hong
2013, 28(1): 55-60.
Abstract(1648) PDF(1023)
Abstract:
Nanoporous carbons with a hierarchical pore structure were prepared by a combination of hard-templating of a thermosetting phenolic resin containing silica nanoparticles, pyrolysis and KOH activation. The influence of the amount of KOH on the pore structure of the templated and activated carbons was investigated by N2 adsorption and the effect of pore structure on the CO2 adsorption capacity was investigated by thermogravimetric analysis. Results indicated that KOH activation promoted the formation of micropores and small mesopores for the templated carbon. The utilization ratio of mesopores for the capture of CO2 is high compared with that of micropores. The porous carbon prepared under a mass ratio of KOH to templated carbon of 2∶1 has both developed mesopores and micropores, and has a largest adsorption capacity for CO2 among all samples investigated.
Preparation of dispersible graphene oxide as a filler to increase the thermal stability of a flame retarding polymer
ZHANG Shu-peng1, 　SONG Hai-ou2
2013, 28(1): 61-65.
Abstract(1481) PDF(1567)
Abstract:
Graphene oxide (GO) was modified with polyethylene glycol mono-methyl ether 750 (MPEG750) by esterification to increase its dispersibility in solvents and a GO/PEG-4000 composite was prepared by solution blending. Results showed that the GO-MPEG750 is dispersible in both polar and nonpolar solvents. The thermal stability of the PEG-4000 could be improved significantly by adding as little as 1 mass% of the GO-MPEG750 in PEG-4000 as a nanofiller. The incipient degradation temperature was increased by 63℃ for the composite, suggesting a promising use of dispersible GO-MPEG750 to increase the thermal stability of flame retardants in industry.
Synthesis and intrinsic magnetic properties of interconnected carbon micro-sphere
WEN Jian-feng1, 2
2013, 28(1): 66-70.
Abstract(1343) PDF(1199)
Abstract:
Interconnected carbon micro-spheres (CMSs) with diameters in the range of 3~5μm were synthesized by acetylene pyrolysis at 750℃ on a SiO2 substrate. The CMSs have a graphitic structure with many intrinsic defects. Results indicate that the CMSs show both diamagnetic and paramagnetic behavior. Intrinsic defects have magnetic moments with spin 1/2. Approximately every 1,000 carbon atoms contribute 1.1μB unpaired spins. The unpaired spins have no interactions with each other and show typical Curie-like paramagnetic behavior.
Grinding texture as a useful surface to reduce the friction of carbide-derived carbon coatings
SUI Jian1, 2, 　LU Jin-jun1
2013, 28(1): 71-75.
Abstract(1439) PDF(1023)
Abstract:
A 150μm thick SiC coating was ground to form V-shaped and U-shaped grooves with a 10μm depth, which was followed by partial chlorination to convert the coating to a carbide-derived carbon (CDC) coating. The effect of the grooves in the CDC coating on its tribological properties was investigated. The grooves were removed by further grinding for comparison. It was found that the grooved CDC coating exhibited improved tribological properties in sliding against Si3N4 in both dry and moist conditions compared with the coating without grooves. The friction coefficient of the grooved CDC coating (0.05) against Si3N4 was lower than that of the ungrooved coating under moist condition,s which can be accounted for by a hydrodynamic lubrication mechanism in the vicinity of the grooves. The grooves were also a useful surface texture to reduce the friction coefficient of the CDC coating in sliding against Si3N4 under dry conditions.
Adsorption of heavy metal ions by carbon-coated iron nanoparitcles for
PANG Jin-shan1|　DENG Ai-hua1
2013, 28(1): 76-80.
Abstract(1367) PDF(1308)
Abstract:
Carbon-coated iron nanoparticles were synthesized by a carbon arc discharge method using electrodes made of iron and graphite powder. The amorphous carbon layer of the carbon-coated iron nanoparticles was treated by a 30% H2O2 aqueous solution. Adsorption of the carbon-coated iron particles for heavy metal ions, such as Cr, Ni, Cd, Pb, Co and Mn, was studied. Results showed that carboxyl and hydroxyl groups were formed on the surface of the amorphous carbon layer after the treatment by hydrogen peroxide. In a strong alkaline medium, the hydroxyl and carboxyl groups increased the electrostatic attraction, and the adsorption performance of the treated carbon-coated iron particles for heavy metal ions was improved. The removal efficiencies for Cr, Ni, Cd, Pb, Co and Mn by the treated carbon-coated iron nanoparticles were all over 90% in a pH range of 8-10 and their adsorption capacity is much higher than that of activated carbons.

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