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采用燃烧法制备了Fe/Mo/MgO催化剂,用化学气相沉积法在1000℃下催化裂解甲烷制得了单壁纳米碳管.实验结果表明,550℃下焙烧的催化剂效果最好,适宜的酸碱性应该是催化剂具有较高活性的原因.用扫描电镜、透射电镜、高分辨透射电镜、热重分析和拉曼光谱等方法对制备的纳米碳管粗产品进行了表征.结果表明,该产物确为高质量单壁纳米碳管,其形态基本都以束状存在,且单壁纳米碳管直径分布较窄(0.85~1.22nm);对反应气氛的考察表明,CH4/N2=50/300为最佳,该气氛下所制得粗产物中单壁碳管的含量接近40%,经稀盐酸室温处理后,碳管含量可达到75%以上. 相似文献
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以纳米碳管和活性碳二元碳材料为催化层碳载体制备了氧扩散电极,采用稳态极化和电化学阻抗技术对其在碱性介质中氧还原反应的电催化活性进行了研究.结果表明,双载体电极比单载体纳米碳管、活性炭电极具有更高的电催化活性,纳米碳管和活性炭质量比为50∶50时双载体电极的催化活性最好;电极动力学参数测试表明,催化层中引入第二相纳米碳管载体提高了电极比表面积、电子导电性和氧还原反应速度;采用浸渍还原法在第二相纳米碳管载体中负载纳米级Pt催化剂,即使在低Pt负载量下(45.7μg/cm2)也明显改善了双载体电极的催化活性.阻抗测试表明,载Pt与未载Pt催化剂的双载体电极均受氧在薄液膜中的扩散控制. 相似文献
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钛基底的纳米金刚石掺混纳米碳管的场发射特性 总被引:1,自引:1,他引:0
在纳米金刚石场发射的基础上, 研究了纳米金刚石掺混纳米碳管的场发射特性。采用电泳沉积法形成了纳米金刚石与纳米碳管的复合涂层, 经热处理后制备出阴极样品, 然后进行微观表征, 再进行场发射特性测试与发光测试。结果表明, 与未掺混的纳米金刚石阴极样品相比, 复合涂层阴极样品的场发射开启电场明显减小, 场发射电流提高, 在较低的电场下阳极表面荧光粉就可以发光, 但发光不均匀, 出现了"边沿发光"的现象。分析了纳米金刚石掺混纳米碳管场发射性能提高的机理, 是由于纳米碳管掺入之后, 涂层的电子输运能力得到增强, 涂层中有效发射体的数目增加。最后, 解释了"边沿发光"现象的成因。 相似文献
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新型螯合磁性纳米Fe_3O_4的制备及其性能研究 总被引:1,自引:1,他引:0
采用共沉淀法制备了磁性四氧化三铁(Fe3O4)纳米粒子,并通过硅烷偶联剂对其表面进行改性,进一步在其表面偶联修饰氨基硫脲,制备了螯合磁性纳米Fe3O4粒子。利用广角X射线衍射仪(WAXD)、红外光谱仪(FTIR)、分光光度计等对磁性纳米粒子的结构和性能进行了表征。结果表明,纳米Fe3O4为反尖晶石结构,通过偶联修饰可以实现氨基硫脲在纳米粒子表面的化学改性。螯合磁性纳米粒子具有良好的分散性和磁响应性,且对多种金属离子(Pb2+、Hg2+、Zn2+、Cd2+)具有良好的螯合效果。 相似文献
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Delong He Yongning Liu Tingkai Zhao Jiewu Zhu Guang Yu 《Journal of nanoparticle research》2008,10(3):409-414
The effect of oxygen on the growth of single-walled carbon nanotubes was studied with Ni–Co alloy powder as catalyst under
helium atmosphere of 500 Torr by electric arc discharge. The oxygen included in nickel or (and) cobalt oxides was added in
catalyst. The content of oxygen in atmosphere was controlled by changing vacuum degree inside furnace before inputting buffer
gas. The examinations of TEM and Raman scattering showed that oxygen in metal oxide as catalyst promotes the nucleation of
SWCNT by taking effect on the metal catalyst particles. However, O2 in atmosphere has the role of oxidizing amorphous particles along with nanotubes. When its molar proportion is higher than
0.22 ppm (Parts per million), the carbon nanotubes produced are oxidized and their purity decreases. The diameter of single-walled
carbon nanotube obtained under different condition has a narrow distribution around 1.28 nm. 相似文献
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《Current Applied Physics》2007,7(1):39-41
We present a route to synthesize polyacetylene filled multi-walled carbon nanotubes (MCNT) by in situ polymerization. We use supercritical carbon dioxide to fill the nanotubes with toluene and then add the Ziegler–Natta catalyst. In order to assure controlled polymerization inside the nanotube, the catalyst outside is removed before the reaction. The resulting polyacetylene filled nanotubes are characterized by 1H NMR and scanning electron microscope. 相似文献
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改变初始温度以及分别使用甲烷和乙炔气体作碳源时气相爆轰合成碳纳米管,研究了初始温度与不同碳源对碳纳米管的影响。利用X射线衍射(XRD)、透射电镜(TEM)、拉曼(Raman)光谱等对碳纳米管进行表征。结果表明,随着初始温度的升高,所合成的碳纳米管的产量减少且石墨化程度降低,但管壁会变得光滑且管径有所增加。当使用乙炔时,所合成的产物中没有碳纳米管,而是合成了石墨化程度较高的无定形碳,随着催化剂量的增加,产物中碳包覆颗粒增多且包覆层清晰可见,但存在结构缺陷。当初始温度在110~130 ℃时,使用甲烷气体运用气相爆轰的手段是合成碳纳米管的较佳方案。 相似文献
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Synthesis and characterization of carbon nanotubes on carbon microfibers by floating catalyst method
Yuxue Xia Leyong Zeng Weibiao Wang Jingqiu Liang Song Chen Haifeng Zhao 《Applied Surface Science》2007,253(16):6807-6810
In this paper, carbon nanotubes were synthesized on carbon microfibers by floating catalyst method with the pretreatment of carbon microfibers at the temperature of 1023 K, using C2H2 as carbon source and N2 as carrier gas. The morphology and microstructure of carbon nanotubes were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The composition of carbon nanotubes was determined by energy dispersive X-ray spectroscopy (EDX). The results showed that the surface of treated carbon microfibers was thickly covered by carbon nanotubes with diameters of about 50 nm. EDX image indicated that the composition of carbon nanotubes was carbon. In comparison with the sample grown on untreated carbon microfibers surface, it was found that after carbon microfibers were boiled in the solution of sulfur acid and nitric acid (VH2SO4:VHNO3 = 1:3) and immersed in the solution of iron nitrate and xylene, carbon nanotubes with uniform density can be grown on carbon microfibers surface. Based on the results, we concluded that the pretreatment of carbon microfibers had great effect on the growth of carbon nanotubes by floating catalyst method. 相似文献
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热丝和射频等离子体化学气相沉积法制备定向碳纳米管薄膜 总被引:1,自引:0,他引:1
采用热丝和射频等离子体复合化学气相沉积设备(PE-HF-CVD),以CH4、H2和N2为反应气体.在较低衬底温度下(500℃),用简单的催化剂制备方法--旋涂法在硅片上涂覆Ni(NO3)2溶液,经热处理及H2还原后的Ni颗粒为催化剂,在硅衬底上制备出了垂直于硅片且定向生长的碳纳米管薄膜.扫描电子显微镜(SEM)和透射电子显微镜(TEM)结果显示,1 mol/l的硝酸镍溶液旋涂硅片所得催化剂制得的碳纳米管管径为30~50 nm,长度超过4μm,定向性好.并用拉曼光谱(Raman)对不同摩尔浓度Ni(NO3)2溶液条件下制备的碳纳米管薄膜样品进行了表征. 相似文献
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Pradip Ghosh T. Soga M. Tanemura M. Zamri T. Jimbo R. Katoh K. Sumiyama 《Applied Physics A: Materials Science & Processing》2009,94(1):51-56
Vertically aligned carbon nanotubes have been synthesized from botanical hydrocarbons: Turpentine oil and Eucalyptus oil on
Si(100) substrate using Fe catalyst by simple spray pyrolysis method at 700°C and at atmospheric pressure. The as-grown carbon
nanotubes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution
TEM (HRTEM), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and Raman spectroscopy. It was observed
that nanotubes grown from turpentine oil have better degree of graphitization and field emission performance than eucalyptus
oil grown carbon nanotubes. The turpentine oil and eucalyptus oil grown carbon nanotubes indicated that the turn-on field
of about 1.7 and 1.93 V/μm, respectively, at 10 μA/cm2. The threshold field was observed to be about 2.13 and 2.9 V/μm at 1 mA/cm2 of nanotubes grown from turpentine oil and eucalyptus oil respectively. Moreover, turpentine oil grown carbon nanotubes show
higher current density in relative to eucalyptus oil grown carbon nanotubes. The maximum current density of 15.3 mA/cm2 was obtained for ∼3 V/μm corresponding to the nanotubes grown from turpentine oil. The improved field emission performance
was attributed to the enhanced crystallinity, fewer defects, and greater length of turpentine oil grown carbon nanotubes. 相似文献
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Guerrero Estefana Muoz-Mrquez Miguel A. Fernndez-Pinel Enrique Crespo Patricia Hernando Antonio Fernndez Asuncin 《Journal of nanoparticle research》2008,10(1):179-189
The present work describes the field emission characteristics of nanocrystalline metal clusters decorated multi walled carbon
nanotubes (MWNT) field emitters fabricated over flexible graphitized carbon cloth. MWNT have been synthesized by catalytic
chemical vapour decomposition (CCVD) of acetylene over Rare Earth (RE) based AB2 (DyNi2) alloy hydride catalyst. Fine powders of RE based AB2 alloy hydride catalysts have been prepared by hydrogen decrepitation technique. The as-grown carbon nanotubes (CNTs) are purified
by acid and heat treatments and characterized using XRD, SEM and TEM. Purified MWNT have been decorated with nanocrystalline
Pd, Pt and Pt–Ru metal clusters using a simple chemical reduction method. The characterization of metal decorated CNTs were
done by using XRD, SEM, TEM, HRTEM and EDX. Nanocrystalline Pd, Pt and Pt–Ru metal clusters decorated MWNT field emitters
have been fabricated over graphitized carbon fabric using spin coating method. The field emission characteristics have been
studied using an indigenously fabricated set up and the results are discussed. The samples show excellent emission properties
with a fairly stable emission current over a period of 4 h. As the presence of the graphitic layer provides strong adhesion
between the nanotubes and carbon cloth, the use of graphitized carbon cloth as substrate opens new possibilities for CNT field
emitters. 相似文献
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J.M. Cao 《Applied Surface Science》2006,253(5):2460-2464
Three-step raising temperature process was employed to fabricate carbon nanotubes by pyrolysis of ferrocene/melamine mixtures on silica and single crystalline silicon wafers respectively. Then the morphologies, structures and compositions of obtained carbon nanotubes are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscope (EDX) and electron energy-loss spectroscopy (EELS). TEM and SEM observation shows that on silica substrate, high-oriented carbon nanotube can grow compactly to form continuous film on both frontal and cross-section surfaces, but on silicon substrate, only can form on cross-section surface. These carbon nanotubes have much irregular cup-like structure, and with outer diameter varying from 25 nm to 35 nm. At the top end of carbon nanotube there is a catalyst particle. EDX analysis reveals that the particle are iron cluster, and EELS spectrum indicates that the nanotube is composed of pure carbon. Finally, the effect of substrate surface roughness on the growth behavior of carbon nanotubes has been discussed. 相似文献
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燃烧法合成碳纳米管的实验方案设计 总被引:2,自引:0,他引:2
碳纳米管是一种新型的碳材料,其合成方法多种多样。燃烧法是一种新兴的合成方法,燃烧过程提供用于碳纳米管生长的高温环境,同时也提供足够的烃原料。目前,用于合成碳纳米管的原料包括气体燃料和液体燃料,火焰类型主要有层流扩散火焰、逆流扩散火焰和预混火焰等。影响炭纳米管火焰合成的因素主要有气体成分,温度,催化剂,燃氧比和采样条件。我们采用甲烷扩散火焰用于实验研究炭纳米管的合成条件。实验系统包括扩散火焰喷嘴,混和段,质量流量计,取样探针和基板,气源。内径5 mm的喷嘴与内径100 mm的钢筒同轴。实验测得在气量为0.20 SLM时火焰高度为 3.5 cm。涂覆有催化剂的基板水平朝下置于火焰中采样,并将采集的样品进行电镜分析。本文还对燃烧法合成碳纳米管的机理进行了分析。 相似文献