新型炭材料

YANG Quan-hong

2007, 22(04): 289-294.

Abstract(2675)

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Abstract:
A new classification for porous carbons is proposed, which is based on the identification of the pore wall structure. Accordingly, nanoporous carbons can be divided into two categories: micrographitebased nanoporous carbon (MGPC) and graphenebased nanoporous carbon (GPC). With similar specific surface area, MGPC and GPC are possibly characterized by different physicochemical properties (e.g. electrochemical properties). Two novel GPCs are introduced in this paper: zeolitetemplated single graphenebased microporous carbon and SWCNTDNA hybrid. Also, how Raman spectroscopy becomes an important tool, for identifying MGPC and GPC, is briefly discussed.

功能性多孔炭材料在突发性环境污染事故中的应用

JIANG Chun-ming, ZHANG Hong-zhe, ZHANG Hai-feng, ZHAO Yong-hua, YUAN Ji-wu, GUO Xiu-yun, QIU Jie-shan

2007, 22(04): 295-301.

Abstract(3352)

PDF(978)

Abstract:
〗The use of functional carbon materials with developed porous structure for wastewater treatment and for removal of spilled oil, and spilled hazardous substances has become increasingly important. The present status and recent progress in using carbon materials as adsorbents in emergency pollution accidents are reviewed. The potential applications in emergency pollution accidents and necessary future work are outlined briefly. It is pointed out that more work is required in terms of exploring effective procedures, optimizing the operation conditions and developing novel carbon materials, which will provide more efficient and costeffective ways for emergency response to deal with the polluting accidents in future.

纳米结构的炭钌复合物—一种提高超级电容器性能的电极材料(英文)

CUI Guang-lei, ZHOU Xin-hong, ZHI Lin-jie, Arne Thomas, Klaus Müllen

2007, 22(04): 302-306.

Abstract(2708)

PDF(933)

Abstract:
Carbon/nano Ru composites were obtained by silica templating of dichlorobis(μ-chloro)bis\[(1-3-η:6-8-η)-2,7-dimethyloctadienediyl\] diruthenium(IV), followed by pyrolysis. Carbon/RuO2·xH2O composites were obtained by electrooxidation of carbon/nano Ru composites. It was found that the carbon/Ru composites had homogeneously dispersed Ru nanoparticles in the hierarchical pore structures and carbon matrix. The carbon/RuO2·xH2O composites displayed improved capacitive properties (229F/g at 10mV/s ) as electrodes of supercapacitors in H2SO4 electrolyte.

硝酸氧化改性SBA-15 模板合成的中孔炭电容性能研究(英文)

WANG Da-wei, LI Feng, LIU Min, CHENG Hui-ming

2007, 22(04): 307-314.

Abstract(2787)

PDF(841)

Abstract:
This study reports modified SBA15 templated mesoporous carbon as a supercapacitor electrode for highefficiency energy storage. Mesoporous carbon was oxidized in concentrated nitric acid at 26℃, 50℃, 70℃, and 100℃. The evolution of mesopores and surface oxygencontaining functional groups (SOFGs) of the mesoporous carbons were studied by nitrogen cryosorption, Xray photoelectron spectroscopy, and thermogravimetric analysis. The results demonstrate that the specific surface area and the mesopore volume decrease, while the SOFGs accumulate with increasing oxidation temperature. The supercapacitor performance was characterized in a KOH aqueous electrolyte. An enhanced energy density with a highest value of 5.7Wh/kg is obtained after oxidation at 100℃ compared to 3.5Wh/kg before oxidation, demonstrating the possibility of using modified mesoporous carbons in high energy density applications. The enhanced energy density is attributed to the contribution of SOFGs to charge storage in both the electric double layer and the Faradic reaction. The power density is also improved with a highest value of 3125W/kg after oxidation at 70℃ compared to the original value of 2015W/kg. The improvement of power density relies on the improved wettability of carbon surfaces, which can facilitate the ion transport.

甲烷催化裂解制备毛线状炭纤维及其微观结构

ZHANG Hua, SHI Jing-li, GUO Quan-gui, WANG Kun-jie, ZHAO Jian-guo, LIU Lang

2007, 22(04): 315-320.

Abstract(3913)

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Abstract:
Interwoven carbon nanofiber yarns were prepared from the catalytic pyrolysis of methane using ferrous sulfate and graphite as catalyst precursor and substrate respectively. They were characterized by SEM, HRTEM, XRD and Raman spectroscopy. Results indicated that the yarns had a diameter of 4 - 8μm and consisted of interwoven carbon nanofibers. The catalyst particle was observed at the root of a yarn. The carbon nanofibers had a crystallite size (La) of about 5nm and the d002 was 0.340nm. The growth of the yarns complied with a adsorptiondiffusionprecipitation mechanism and the diameter of yarn was determined by the size of the catalyst particle.

由柏木制备纳米孔结构炭材料II.电双层电容器中的应用(英文)

2007, 22(04): 321-326.

Abstract(2310)

PDF(815)

Abstract:
Cypress charcoals, which were prepared under superheated steam and had a relatively large amount of mesopores, were used in electric double layer capacitors (EDLCs) in 1mol/L H2SO4 electrolyte. The gravimetric capacitance of cypress charcoals was about 190F/g at a current density of 50mA/g (C50) and 140F/g at 1000mA/g (C1000) and the performance rating defined by C1000/C50 was about 0.72. The capacitance observed was explained by the contributions from the surfaces from the micropores and the larger pores. By loading minute NiO particles through a simple impregnating process, the capacitance of the loaded charcoals was enhanced by about 13% in gravimetric capacitance and by about 27% in volumetric capacitance and the performance rating was kept the same.

PyC/SiC界面相对PIP法制备3D HTA C/SiC复合材料性能的影响(英文)

ZHU Yun-zhou, HUANG Zheng-ren, DONG Shao-ming

2007, 22(04): 327-331.

Abstract(2457)

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Abstract:
3D braided carbon fiber preforms were used to fabricate C/SiC composites using polymer infiltration and pyrolysis (PIP). Before the PIP, the preforms were coated by isothermal chemical vapor infiltration with methane to produce pyrocarbon (PyC) and then with hexamethyldisilazane to form SiC and produce the PyC/SiC interphase. The correlation of the PyC/SiC interphase to the microstructure and the mechanical properties of the fabricated composites was investigated. The flexural properties of the composites were measured using the threepointbend test, and the fracture surfaces observed by SEM. The bend strengths were 247MPa and 46MPa, with and without the PyC/SiC interphase respectively. Long fiber pullout dominated the fracture surface for the composite with the PyC/SiC interphase, while for the one without the interphase, almost no fiber pullout was observed.

水中电弧法制备碳纳米葱

JIANG Peng, YAO Ke-fu

2007, 22(04): 332-336.

Abstract(2051)

PDF(520)

Abstract:
Carbon nanoonions were synthesized by arcdischarge with graphite electrodes submerged in water. The products were characterized by Raman spectroscopy and highresolution transmission electron microscopy. It was found that the density of the arcdischarge current had a significant influence on the morphologies and the output of the products, which aggregated near the surface of the water or precipitated on the bottom. When the current used was about 40A, the products collected near the surface of the water were wellcrystallized spherical carbon nanoonions, 520nm in diameter, and the output capacity was about 4.3mg/min, indicating that a large amount of high quality nanocarbononions could be prepared by this technique.

水或液氮中电弧放电制备炭纳米材料(英文)

XING Gang, JIA Shen-li, SHI Zong-qian

2007, 22(04): 337-341.

Abstract(2444)

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Abstract:
The growth mechanism of carbon nanomaterials by arc discharge in water or liquid nitrogen was investigated using a special arc discharge apparatus. Highresolution transmission electron microscopy was used to observe and analyze the products. Results indicated that multiwalled carbon nanotubes (MWCNTs) and carbon onions can be produced by arc discharge in water and liquid nitrogen respectively. Singlewalled carbon nanohorns can be produced by arc discharge in liquid nitrogen, and cobalt encapsulated carbon nanoparticles can be produced by cobalt catalyzed carbon arc discharge in water. The liquids acted as quenching walls for the nucleation and growth of carbon nanomaterials, resulting in the formation of different forms of carbon nanomaterials. A cross alternating magnetic field with a frequency 5Hz can affect the nucleation of nanomaterials to form MWCNTs or carbon onions because nucleation time is longer than the periodicity of the magnetic field. Based on the experimental phenomena, a primary physical model was proposed to interpret the growth of nanomaterials by arc discharge in liquids.

HClO4-GIC的制备及其柔性石墨的性能

WEI Xing-hai, LIU Lang, ZHANG Jin-xi, SHI Jing-li, GUO Quan-gui

2007, 22(04): 342-348.

Abstract(2716)

PDF(807)

Abstract:
HClO4-GICs were prepared by a chemical method using natural graphite flake, perchloric acid and concentrated nitric acid as host material, intercalating agent and catalyst, respectively. The GICs were exfoliated to make exfoliated graphite. Flexible graphite was made by compressive molding of the exfoliated graphite, and was characterized by mechanical and thermal/electrical testing. An orthogonal experimental design method was used to investigate the effects of reaction temperature and time, expansion temperature and the HClO4GIC volatiles on the exfoliation volume of the exfoliated graphite. It was found that HClO4GIC could be synthesized at temperatures from ambient to 100℃ by HClO4/HNO3 impregnation. The descending order of factors affecting exfoliation volume was reaction temperature, weight ratio of HClO4 to HNO3, reaction time and weight ratio of graphite flake to HClO4. Under the optimum conditions with the weight ratio of natural flake graphite∶perchloric acid∶nitric acid being 1∶4∶0.15, reaction time of 15min, and reaction temperature of 100℃, the exfoliated graphite obtained at 200℃ and 900℃ had exfoliation volumes of 360mL/g and 540mL/g respectively. With increasing density, the tensile strength of the flexible graphite increased, electrical resistivity decreased and the thermal conductivity increased. The thermal conductivity of flexible graphite is higher than a carbon/graphite composite with the same electrical resistivity.

基于RBF神经网络的添加剂改性炭材料高温黏结剂的性能预报模型

YANG Zhen, GU Xing-sheng, LIANG Xiao-yi, ZHANG Rui, LING Li-cheng

2007, 22(04): 349-354.

Abstract(2972)

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Abstract:
A radial basis function（RBF）neural network predictive model was applied to the experimental data on additive of high temperature binder to join carbon materials. The predictive accuracy and the training process using a RBF neural network were compared with those of a backpropagation (BP) neural network. Results showed that the average relative errors of two such models were 0.0127 and 0.0600 for RBF and BP model respectively and BP neural network was easy to fall into a local minimum. Therefore, the RBF neural network predictive model was better than the BP model. It is expected that the RBF neural network can be used in multivariable, nonlinear system to quickly optimize experimental parameters, such as the optimum amount of binder that should be added to the carbon material to achieve a particular property.

高性能活性炭电极材料在双电层电容器中的应用

LIU Ya-fei, HU Zhong-hua, REN Lian-wen, YNAG Jing, CHEN Xiao-mei

2007, 22(04): 355-360.

Abstract(2580)

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Abstract:
Activated carbons (ACs) were prepared by simultaneous physicalchemical activation of coconut shells using ZnCl2 as activating agent. Their specific surface area and porosity parameters were calculated from the nitrogen adsorptiondesorption isotherms at 77K. The electrochemical properties of the electric double layer capacitors using these ACs as electrode materials were studied by a constant current chargedischarge technique and cyclic voltammetry. Results indicated that the specific capacitance of the carbon material could be as high as 360F/g at a low discharge current of 5mA, and it remained above 200F/g at a larger discharge current of 50mA. The influence of specific surface area and pore size on the electrochemical property was investigated. No special relationship was found between specific surface area and specific capacitance. However, the pore size had a significant influence on the specific capacitance. In a discharge at small current, the contribution of mesopore surface to the electric doublelayer capacitance was larger than that of micropores. With increasing discharge current, the capacitance of mesopore surface decreased faster than that of micorpore surface. For discharge at a large current, supermicropores of 1.5 - 2nm played an important role for the electrical energy storage.

纳米炭复合物导电剂改进LiCoO2阴极的电化学性能(英文)

ZHANG Qing-tang, QU Mei-zhen, NIU Hong, YU Zuo-long

2007, 22(04): 361-364.

Abstract(2654)

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Abstract:
Nanocarbon composites (NCCs), which were formed by sonication of multiwalled carbon nanotubes (MWCNTs) and acetylene black (AB), were used as a conducting additive in a LiCoO2 cathode for lithium ion batteries. The electrochemical performance of LiCoO2 cathode dispersed with NCC was investigated. The results showed that the electrochemical performance (including the initial discharge capacity and the capacity retention) of a NCCloaded LiCoO2 cathode were better than that of a cathode loaded with MWCNTs or AB, which can be ascribed to the superior conducting networks formed in NCC, compared to MWCNTs or AB, and the good and stable contact between NCC and LiCoO2 particles.

新型定向碳纳米管/炭复合材料的制备与表征

LI Zhi, GONG Qian-ming, WANG Ye, LIANG Ji, HUANG Qi-zhong, XIONG Xiang, YI Mao-zhong, HUANG Bai-yun

2007, 22(04): 365-370.

Abstract(2820)

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Abstract:
Long aligned carbon nanotube (ACNT) arrays over 4mm thick were prepared by chemical vapor deposition by adjusting processing parameters. ACNT/C composites were fabricated by densifying the ACNTs with chemical vapor infiltration, and were characterized by SEM, PLM, XRD, TGA and Raman spectroscopy. It was found that the pyrocarbon was mainly of the rough lamella type for ACNT/C composites compared with the typically smooth lamella type for traditional carbon/carbon (C/C) composites, in spite of using the same process. Pyrocabon around CNTs showed a high degree of crystallization. The temperature at which ACNT/C composites began to show a weight loss in air was about 50℃ higher than that for C/C composites.

Fe3 O4包覆碳纳米管软磁性纳米复合微粒的制备及性能

JIANG Feng-jing, PU Hong-ting, YANG Zheng-long, YIN Jun-lin

2007, 22(04): 371-374.

Abstract(2373)

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Abstract:
Carbon nanotube (CNT)/Fe3O4 composites were prepared by depositing Fe3O4 onto CNTs. The morphologies, magnetic properties, sedimentation stability and magnetorheological properties of the composite particles were investigated by transmission electron microscopy, vibrating sample magnetometer, and a viscosimeter with magnetic equipment. The diameter of CNT/Fe3O4 nanoparticles is about 60nm, while that of CNTs is about 20nm. The average density of the CNT/Fe3O4 nanoparticles is about 1.8g/cm3, which is only onefourth of the normal soft magnetic particles based on Fe3O4 or Fe powder. The CNT/Fe3O4 composites have a similar magnetic hysteresis loops to that of Fe3O4, indicating the good soft magnetic properties of the composite particles. The saturation induction density (Bs) of the composite particles is 0.21T，and the coercive force (Hc) is 7.67kA/m. Magnetorheological fluids based on such CNT/Fe3O4 composites show high sedimentation stability and good magnetorheological properties.

碳纳米管加载量对复合材料吸波性能的影响

SUN Xiao-gang

2007, 22(04): 375-378.

Abstract(4478)

PDF(739)

Abstract:
The radar wave absorbing properties of carbon nanotube based composites were investigated. Carbon nanotubes were added to epoxy resin with different weights and dispersed by sonication to prepare radar absorption composite materials (RAM). Then the composite paste was put into an aluminium pan to form the test sample. Carbon nanotubes were characterized by TEM and radar absorbing properties were obtained by the arc reflectivity method. Results indicate that carbon nanotubes have excellent radar absorbing properties in the waveband of 218GHz. The best parameters are obtained using mass fraction carbon nanotube additions of 8% and 10%. The highest absorbing peak of -22.55dB at 12.32GHz is obtained for the composite with an addition of 8% carbon nanotubes and the composite has a bandwidth of 2.56GHz at R<-8dB and 4.00GHz at R<-5dB. With an addition of 10%, the absorbing peak of -14.59dB is located at 13.67GHz with the largest bandwidths of 2.80GHz at R<-8dB and 7.00GHz at R<-5dB.

Ar离子轰击高定向石墨表面结构变化的X射线光电子能谱分析

LIU Li-ming, YANG Pei-zhi, HUANG Zong-tan

2007, 22(04): 379-382.

Abstract(2209)

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Abstract:
Surface structure changes of high oriented pyrolytic graphite induced by 3.0keV Ar ion bombardment were studied using Xray photoelectron spectroscopy （XPS）. The spectra, including C1s, Xrayexcited Auger electron spectroscopy and XPS valence band spectroscopy were analyzed qualitatively and quantitatively. Results show that the conjugated π bond can be destroyed and local sp2 hybridized carbon can be developed into sp3 hybridized carbon by Ar ion bombardment. The ratio of sp3 to sp2 depends on the bombardment time.

2007 Vol. 22, No. 04

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