新型炭材料

YANG Yong-gang, CHEN Cheng-meng, WEN Yue-fang, YANG Quan-hong, WANG Mao-zhang

2008, 23(03): 193-200.

Abstract(4912)

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Abstract:
Graphene sheets—oneatomthick twodimensional layers of sp2bonded carbon—are novel nanofillers for composites with many unique properties. Graphene has attracted much attention from physical and materials scientists since became available in 2004. Here the preparation, characterization and modification routes of oxidized graphite, oxidized graphene and graphene based polymer composites are reviewed. Future research and possible applications are also discussed. Largescale synthesis and application of oxidized graphene sheets can be achieved by mechanical exfoliation of graphite oxide, further chemical functionalization and dispersion in a polymer matrix. Such a method has become a strategic starting point for the industrial application of graphene, and remarkable progress has been made in the last few years.

反复拉伸法制备单壁碳纳米管定向排列的SWCNT/PMMA复合材料

DAI Jian-feng, ZHANG Chao, WANG Qing, LI Wei-xue, YAO Dong

2008, 23(03): 201-204.

Abstract(3201)

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SWCNT/polymethylmethacrylate (SWCNT/PMMA) composites with SWCNTs uniformly dispersed and aligned within the polymer were fabricated by a repeated stretching. A semidried mixture of SWCNTs and PMMA was treated in turn by stretching at a drawing ratio of 50 and folding, and the treatment was repeated 100times. SEM and polarized Raman spectra demonstrated that the SWCNTs in the composites tended to align in the stretching direction. The electrical conductivity and the mechanical properties of the composites improve with SWCNT concentration. The composites showed a higher electrical conductivity and improved mechanical properties such as Young’s modulus, tensile strength and elongation along the stretching direction than those along the perpendicular direction.

炭化聚甲基丙烯酸甲酯/聚丙烯腈核壳聚合物制备炭纳米空心球

YANG Guang-zhi, XU Ri-sheng, CHEN Min, WANG Xia, LING Li-cheng, ZHANG Rui, YANG Jun-he

2008, 23(03): 205-208.

Abstract(2662)

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Hollow carbon nanospheres (HCNs) were synthesized by carbonizing fine core/shell particles of polymethylmethacrylate (PMMA)/polyacrylonitrile (PAN). The PMMA/PAN core/shell particles were prepared using twostage soapless emulsion polymerization. PMMA spheres with a diameter of approximately 200nm were first synthesised by batch mode polymerization and then a PAN shell with a thickness of approximately 30nm was polymerized on the surface of PMMA spheres by dropwise addition of acrylonitrile monomer. After freeze drying, PMMA/PAN composite particles were stabilized in air at 250℃ and then carbonized in nitrogen at 1000℃. Transmission electron microscopy of the final sample showed that all PMMA cores turned into pores and all PAN shells developed into carbon shells. The PMMA/PAN composite particles were converted to HCNs with some adhering with each other and some breaking of the carbon shells.

利用前后处理技术改进钛/硅基板上的类金刚石场发射特性

Bohr-Ran Huang, Chun-Shin Yeh, Shih-Fong Lee, Dau-Chung Wang, Kun-Gi Chen

2008, 23(03): 209-215.

Abstract(3862)

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Abstract:
Diamondlike carbon (DLC) films were deposited on titanium/silicon substrates with the help of the microwave plasma chemical vapor deposition (CVD) method with Ar, H2, and CH4 as a mixed gas source. Titanium/silicon substrates were polished by diamond powder and etched by hydrogen (H2) plasma, prior to deposition. After deposition, rapid thermal annealing (RTA) was used as a posttreatment. The effects of hydrogen plasma pretreatment and RTA posttreatment on the electron field emission characteristics of the DLC films was examined and correlated by Raman scattering, average surface roughness, and surface morphology. It is found that both treatments can improve the field emission characteristics of DLC films. However, RTA posttreatment demonstrates a more pronounced effect on the enhancement of field emission than does the hydrogen plasma pretreatment. This improvement is attributed in part to the increase in surface roughness resulting from sp2 clustering formed during the RTA. The tips of these sp2 clusters provide plenty of efficient emission sites on the surface of the DLC films. Another reason for this improvement is the graphenelike layers formed during the RTA, which provide efficient conduction paths for electrons to move through the DLC films. The field emission characteristics of CVD deposited on DLC films can be greatly enhanced by appropriate pretreatment and posttreatment, leading to promising applications for cold cathodes.

用于空气中水蒸气吸-脱附的微孔泡沫炭制备研究

Naoto Ohta, Yoko Nishi, Takahiro Morishita, Yumiko Ieko, Akifumi Ito, Michio Inagaki

2008, 23(03): 216-220.

Abstract(2378)

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Microporous carbon foams were prepared from a fluorinated polyimide using melamine foam as a template. The adsorption/desorption behavior of water vapor in ambient air was examined. The activation of carbon foams at 400℃ for 1h in air was found to be effective in increasing the adsorptivity of water vapor. The amount of water vapor adsorbed after air activation was almost 3times as large as that before activation, although the micropore volume increase was only 1.5times. The reversible adsorptivity for water vapor in ambient air showed a linear dependence on micropore volume with an adsorptivity of about 40% mass fraction for a micropore volume of 0.75mL/g.

有序介孔炭合成、改性及其对汞离子的吸附性能

ZHU Jian-Zhong, YANG Jia, DENG Bao-Lin

2008, 23(03): 221-227.

Abstract(3408)

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Abstract:
An ordered mesoporous carbon (OMC) was synthesized by in situ polymerization of acrylic acid in an ordered silica template (SBA15), followed by carbonization and template removal. The OMC was subsequently functionalized with ethylenediamine by a combined treatment of nitric acid and thionyl chloride to obtain a functionalized ordered mesoporous carbon (FOMC). This was characterized by SEMEDS, XRD, FTIR and nitrogen adsorption and evaluated for mercuric ion sorption from the aqueous phase. It was found that OMC and FOMC had an ordered mesoporous structure, with surface area, average pore size and pore volume of 607m2/g, 4.1nm, 0.62cm3/g and 558m2/g， 3.8nm， 0.58cm3/g, respectively. The treatments using nitric acid and thionyl chloride were effective to add the amine ligands to the OMC. Mercury sorption kinetics and equilibrium isotherms showed that the Hg(II) sorption capacity of FOMC was double that of OMC, suggesting a high affinity of the aminecontaining FOMC for Hg(II) ions.

通过碳纳米管与硫化锌纳米晶体复合提高硫化锌的光催化活性

FENG Shou-ai, ZHAO Jiang-hong, ZHU Zhen-ping

2008, 23(03): 228-234.

Abstract(3081)

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Carbon nanotubes with attached ZnS nanocrystals were prepared by a reaction between Zn(NO3)2 and Na2S in an aqueous suspension of carbon nanotubes. Postrefluxing treatment and the order in which the reactants were introduced played a crucial role in the improvement of the interaction between ZnS nanocrystals and carbon nanotubes. Studies on methylene blue degradation revealed that carbon nanotubes could effectively increase the photocatalytic activity of the ZnS nanocrystals. Close contact between carbon nanotubes and the ZnS improved the interfacial electron transfer and restrained the electron/hole (e-/h+) pair recombination of ZnS.

低能甲烷和氢气混合离子束诱导产生石墨纳米晶包覆多壁碳纳米管的复合结构

LI Qin-Tao, NI Zhi-Chun, GONG Jin-Long, ZHU De-Zhang, ZHU Zhi-Yuan

2008, 23(03): 235-240.

Abstract(2696)

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Nanographite (NG) deposits were formed on multiwalled carbon nanotubes (MWCNTs) lying on a singlecrystalsilicon plane by irradiating them with an 80eV ion beam perpendicular to the plane. The ion beam was produced using a methane and hydrogen mixture (1∶5) at 700℃. Electron microscopy indicates that there is an angle in the range 45° -90° between the (0002) planes of the formed NG particles and the axis of the MWCNTs. The MWCNTs retained their inner hollow structure. The formation of the NGs can be ascribed to the high temperature decomposition and deposition of methane, and the observation of specific angles (45°-90° ) between the (0002) planes of the NGs and the MWCNT axis may be attributed to the selective etching, or removal, by the hydrogen ions of NG nuclei with 0°-45° between their (0002) planes and the MWCNT axis.

石墨表层对四面体非晶炭膜中受激电子的石墨建序化作用

LIANG Shi-jin, Tatsuya Banno, Yutaka Mera, Masahiro Kitajima, Kunie Ishioka, Yoshihisa Harada, Yoshinori Kitajima, Shik Shin, Koji Maeda

2008, 23(03): 241-244.

Abstract(3039)

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Electronstimulated graphitic ordering in tetrahedral amorphous carbon (taC) films was found to be affected by the removal of the graphitic surface layer present in asdeposited films. To remove the graphitic layer on taC films fabricated by the filtered cathodic vacuum arc method, the sample was etched with oxygen plasma. The removal of the surface layer was examined by transmission electron energy loss spectroscopy, surfaceenhanced Raman spectroscopy, and surfacesensitive Xray absorption spectroscopic measurements. The electronstimulated graphitization was retarded in oxygen plasma etched samples presumably owing to the lack of graphitic nuclei for heterogeneous nucleation.

微波PCVD法大尺寸透明自支撑金刚石膜的制备及红外透过率

LI Bo, HAN Bai, LU Xian-yi, LI Hong-dong, WANG Jian-bo, JIN Zeng-sun

2008, 23(03): 245-249.

Abstract(2662)

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Abstract:
Largesized freestanding transparent diamond films of 50mm diameter and 300μm thickness were prepared by microwave plasma chemical vapor deposition (MWPCVD). The growth rate of the diamond film was only 12μm/h when the diamond film was grown at a methane concentration of 2%, and the infrared (IR) transmittance reached 70% in the range of 5004000cm-1 after the film was polished on both sides. A high growth rate of 78μm/h was achieved for the film grown at a methane concentration of 4%. The thickness of the film was 260μm after it was polished on both sides and its IR transmittance in the range of 5004000cm-1 reached about 60%. Meanwhile, the IR transmittance was almost the same in the central and fringe regions. These results imply a promising application of largesized thick diamond films in IR windows.

微波等离子体化学气相沉积法在硅片上同时生长碳化硅和金刚石

TANG Chun-jiu, FU Lian-she, A. J.S. Fernandes, M. J. Soares, Gil Cabral, A.J. Neves, J. Grácio

2008, 23(03): 250-258.

Abstract(2632)

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Abstract:
The effects of several process parameters, such as substrate temperature, nucleation density, and substrate surface pretreatment, on the simultaneous formation of SiC and diamond under typical growth conditions of diamond by microwave plasma assisted chemical vapor deposition (MPCVD), have been investigated by scanning electron microscopy (SEM), Xray diffraction, and Raman and Fouriertransfer infrared (FTIR) spectroscopy. Results show that no SiC can be detected in the diamond films grown with a high nucleation density, whereas, SiC is detected in the thick diamond films grown with a low nucleation density, with or without surface pretreatment of the Si substrates. SEM micrographs and FTIR spectra illustrate that SiC is formed on the Si substrate not covered by diamond nuclei or in void regions between diamond nuclei. The formation of SiC and diamond on Si substrates under the growth conditions of diamond by MPCVD is a concurrent competitive deposition process, especially at the initial stage of diamond nucleation and growth. This is an alternative method for the synthesis of diamondSiC composites by MPCVD.

单根沥青基炭纤维热导率的温度特性研究

WANG Jian-li, GU Ming, MA Wei-gang, ZHANG Xing, SONG Yan

2008, 23(03): 259-263.

Abstract(2784)

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The thermal conductivity of individual pitchderived carbon fibers was measured in the temperature range 100400K by a T type method, in which a hot wire served both as a heating source and thermometer, and the electrical and thermal properties of the hot wire were measured by direct current heating. When a tested carbon fiber was attached to the center position of the hot wire, the thermal conductivity of the fiber was determined by a comparison of the average temperature rise of the hot wire with and without the fiber. Results show that the thermal conductivity of the fiber was limited by boundary scattering below 300K, and saturated around 350K at a value of about 800W/(m · K). An unexpectedly high thermal conductivity of about 920W/(m · K) was observed at around 400K. The effect of the thermal contact resistance on the measurement was estimated by changing the length of the fiber in the same contact conditions and the radiation effect was also discussed. The uncertainty of the thermal conductivity was estimated to be ±13%.

预氧化处理对聚醚酰亚胺基炭膜结构与气体分离性能的影响

WANG Tong-hua, HU Li-hong, LIU Qing-ling, LIU Shi-li, WANG Zhen, DING Meng-xian

2008, 23(03): 264-268.

Abstract(2891)

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Polyetherimide derived carbon membranes were prepared by pretreating the precursor in air before carbonization at 700℃. The chemical structure, microstructure and gas separation properties of these membranes pretreated at 400, 460 and 480℃ were characterized by FTIR, elemental analysis, XRD and gas permeation tests. The effects of preoxidization on their microstructure and gas separation properties were investigated. Results show that decomposition and oxidationinduced crosslinking reactions occur during the pretreatment. The higher the preoxidization temperature, the higher the degree of decomposition and the degree of crosslinking. After carbonization, the pretreated membranes have an amorphous structure. The differences in the crosslinked structure generated in the pretreatment leads to differences in the micropore structure of the membranes, which can be used to tune gas separation properties. The permeability of all gases investigated exhibits a maximum with a preoxidization temperature at 460℃, for which the O2 permeability is 8.2×10-13(m3(STP) · cm)/(m2 · s · Pa)and the O2/N2 selectivity is 14.1.

掺锰活性炭的制备及其电化学性能

LI Lan-ting, HAO Li-na, ZHANG Jun, WANG Guang-chang, XIE Qiang

2008, 23(03): 269-274.

Abstract(2867)

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A MnOxdoped mesoporous activated carbon (ACMnOx) and an activated carbon (AC) were prepared with and without Mncontaining additives. The microstructure and properties, such as pore volume, pore size distribution, iodine value and methylene blue value, were determined. The electrochemical performance of the two activated carbons as electrodes for electrochemical capacitors were characterized by cyclic voltammetry, AC impedance and chargedischarge at a constant current. Results show that the yield and iodine value of ACMnOx are lowered by 28.9% and 12.4% respectively compared to AC . The methylene blue value of ACMnOx is increased by 19.8% compared to AC. Moreover, ACMnOx has more mesopores than does AC, especially in the range 3.44.2nm. The specific capacitance of an ACMnOx electrode is 93.8F/g, which is 140% of that of an AC electrode, indicating that energy density and pseudocapacitance of the ACMnOx electrode are higher than those of AC electrode.

超级电容器用聚苯胺/活性炭复合电极的研究

WANG Qin, LI Jian-ling, GAO Fei, LI Wen-sheng, WU Ke-zhong, WANG Xin-dong

2008, 23(03): 275-280.

Abstract(3328)

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Abstract:
The performance of activated carbons coated with polyaniline (PANIC) by polymerization of aniline using cyclic voltammetry was investigated as an electrode for supercapacitors by scanning electron microscopy, electrochemical impedance spectroscopy, and constant current charge/discharge measurement. Results showed that a PANI thin film was uniformly deposited on the surface of the activated carbon, forming an interlinked porous network. The PANIC composite electrodes had better cycling stability than PANI electrodes and the specific capacitance of the composite electrodes was 587F/g, which was much higher than that of the pristine activated carbon (140F/g), owing to the faradic reaction of PANI with the electrolyte. The PANI electrode was less stable than the PANIC composite electrode with a capacitance decay from 513 to 334F/g for the former and 415 to 385 for the latter, after 50cycles.

可溶性酚醛树脂为碳源合成有序介孔炭及其电催化性能

CHEN Xiu, HE Jian-ping, DANG Wang-juan, ZHOU Jian-hua, WANG Tao, ZHANG Chuan-xiang, ZHAO Gui-wang

2008, 23(03): 281-288.

Abstract(3241)

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Ordered mesoporous carbons (OMC) were prepared by high temperature carbonization of insitu synthesized phenolic resol from phenol and formaldehyde within ordered mesoporous silica SBA-15 and of mixture of SBA-15 and phenolic resol prepared in advance. These are denoted C1 and C2 respectively. Pt/C1, Pt/C2 and Pt/CMK-5 (furfural as carbon precursor) electrocatalysts were prepared by a microwaveassisted polyol process. The microstructure of the samples was characterized by XRD, TEM and nitrogen adsorption. The performance of Pt loaded samples for methanol electrooxidation was characterized by cyclic voltammetry (CV). Results show that C1 has an ordered hexagonal (P6mm symmetry) mesoporous structure with a BET surface area of 947m2/g and a sharp pore size distribution around 4.5nm. The Pt nanoparticles are uniformly dispersed on C1 with an average diameter of 3nm, while for. C2 the pores are somewhat disordered and the Pt nanoparticles are agglomerated. The CV curves indicate that Pt/C1 exhibits a higher electrocatalytic activity for methanol electrooxidation than do Pt/C2 and Pt/CMK-5 and a little bit lower activity than does commercial ETEK Pt/C. The electrochemically active surface area of Pt/C1 is 54.2m2/g.

2008 Vol. 23, No. 03

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