共查询到20条相似文献,搜索用时 15 毫秒
1.
《Journal of Experimental Nanoscience》2013,8(4):399-408
Synthesis and growth of carbon nanotubes (CNTs) from C2H2 by thermal chemical vapour deposition (TCVD) using a mixture of different gases were investigated. A thin film of nickel was coated as catalyst on silicon substrates by ion beam sputtering technique. Various parameters such as thickness of oxide layer and time, as well as reduction temperature were investigated in view of obtaining the best conditions for CNTs growth. C2H2 was very effective as carbon feedstock and NH3 pretreatments were crucial steps towards obtaining a high density of nucleation sites for CNTs growth by inhibiting amorphous carbon generation in the initial stage of the synthesis. The substrate oxide layer was analysed by secondary ion mass spectrometry. The prepared CNTs were confirmed by Raman spectroscopy and were further characterised using scanning electron microscopy and transmission electron microscopy. 相似文献
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《Journal of Experimental Nanoscience》2013,8(6):797-807
The focus of this research was towards the improvement of the performance of proton exchange membrane fuel cells. The overarching goals were: (1) providing guidelines for design of new catalysts; (2) promoting nanocatalyst applications towards alternative energy applications; and (3) integrating advanced instrumentation into nanocharacterisation and fuel cell (FC) electrochemical behaviour. In tandem with these goals, the cathode catalysts were extensively refined to improve FC performance and minimise noble metal usage. In this study, the major accomplishment was producing aligned carbon nanotubes (ACNT), which were then modified by platinum (Pt) nanoparticles via a post-synthesis colloidal chemistry approach. The Pt-ACNTs demonstrated improved cathodic catalytic activity, as a result of incorporation of the nanotubes with the additional advantage of decreased Pt loading. It was also determined that surface mechanical properties, such as elastic modulus and hardness were increased. Collectively, these enhancements provided an improved FC performance. 相似文献
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采用自制的实验装置, 通过阳极弧放电等离子体技术成功制备了Ni纳米颗粒填充的碳纳米管, 利用高分辨透射电子显微镜(HRTEM)、 XRD、 TEM、 X射线能量色散分析谱仪(XEDS)和振动样品磁强计(VSM)等测试手段对样品的化学成分、 形态、 微观结构和磁性能进行了表征。实验结果表明, 采用本文中实验方法能获得大量被纳米金属颗粒填充的碳纳米管, 其内部填充物为面心立方(FCC)结构的纳米Ni颗粒, 外围薄层为石墨碳层。碳纳米管的外径为30~40 nm, 壁厚5~8 nm, 内部填充的纳米颗粒呈球形和椭球形, 粒径均匀, 在管腔内不连续分布。产物具有顺磁特性, 矫顽力是78 Oe, 饱和磁化强度是33 enu/g。 相似文献
4.
A new approach to chemical vapour deposition (CVD) growth of carbon nanotubes (CNTs) using commercial magnetite nanoparticles, avoiding its in situ synthesis, is reported. Commercial magnetite nanoparticles were used as catalyst material to growth multiwalled carbon nanotubes by chemical vapour deposition onto a silicon substrate of several square centimeters in area. It is shown that the application of an alternating electric field during the deposition of catalytical nanoparticles is an effective technique to avoid their agglomeration allowing nanotube growth. Scanning electron microscopy showed that the nanotubes grow perpendicularly to the substrate and formed an aligned nanotubes array. The array density can be controlled by modifying the deposited nanoparticle concentration. 相似文献
5.
Chun-mei ZHANG Ya-bo FU Qiang CHEN Yue-fei ZHANG 《Frontiers of Materials Science in China》2008,2(1):37-41
Multiwall carbon nanotubes (MWCNTs) were grown by dielectric barrier discharge (DBD)-type plasma enhanced chemical vapor deposition
(PECVD) method in downstream. The temperature was 973 K and the compositions of gases were methane, hydrogen and oxygen in
the total pressure of 0.05 MPa. The effect of O2 concentration in the mixture on the configuration of carbon nanotubes (CNTs) was investigated in detail. Results from scanning
electron microscope (SEM) and transmission electron microscope (TEM) showed that CNTs grown in CH4/H2 (38.6%/61.4%, volume) mixture have many defects and contained disordered graphitic materials. With the addition of appropriate
amount of O2 (∼0.67%), high-purity CNTs could be obtained. However, no CNT, even no carbon matrix existed under the condition of an excessive
oxygen concentration (>1.0%, volume) in the mixture. In order to understand the role of O2 during CNTs growth, optical emission spectroscopy (OES) was in-situ employed and the results predicted that the improvement of CNTs quality in O2 addition was attributed to the effect of OH oxidation from the reaction of atomic oxygen with hydrogen in the plasma. 相似文献
6.
Nitrogen-doped multi-walled carbon nanotubes (N-MWCNT) were selectively grown on oxidised silicon substrate by means of catalytic chemical vapour deposition with decomposition of acetonitrile in the presence of ferrocene (FeCp2) at 900°C. The synthesised N-MWCNT film was initially treated with continuous ozone flow for various time periods and characterised by means of scanning electron microscopy and Raman spectroscopy. The electrochemical response of ozone-treated N-MWCNT film towards ferrocyanide/ferricyanide, [Fe(CN)6]3?/4? redox couple was investigated by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy. The results were compared with those obtained for untreated N-MWCNT film. The findings reveal the occurrence of structural defects on surface of ozone-treated N-MWCNT film due to oxidation of nanotubes. Furthermore, the handling of N-MWCNT film with ozone increases the barrier for interfacial electron transfer and slows down the kinetics of redox reaction occurring on this particular electrode. 相似文献
7.
A novel process is demonstrated whereby dense arrays of single-walled carbon nanotubes (SWNT) are grown directly at the interface
of a carbon material or carbon fiber. This growth process combines the concepts of SWNT tip growth and alumina-supported SWNT
base growth to yield what we refer to as “odako” growth. In odako growth, an alumina flake detaches from the carbon surface
and supports catalytic growth of dense SWNT arrays at the tip, leaving a direct interface between the carbon surface and the
dense SWNT arrays. In addition to being a new and novel form of SWNT array growth, this technique provides a route toward
future development of many important applications for dense aligned SWNT arrays.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.
This article is published with open access at Springerlink.com 相似文献
8.
《Journal of Experimental Nanoscience》2013,8(6):498-508
Bundles of aligned carbon nanotubes (ACNTs) have been synthesised by spray pyrolysis of turpentine oil (inexpensive precursor) and ferrocene mixture at 800°C. Turpentine oil (C10H16), a plant-based precursor was used as a source of carbon and argon as a carrier gas. The bundles of ACNTs have been grown directly inside the quartz tube. The as-grown ACNTs have been characterised through X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopic techniques. Scanning electron microscope images reveal that the bundles of ACNTs are densely packed and are of ~70–130?µm in length. High-resolution transmission electron microscopy and Raman spectroscopy observations indicate that as-grown multi-walled carbon nanotubes (CNTs) are well graphitised. These CNTs have been found to have outer diameters between ~15 and 40?nm. This technique suggests a low-cost route for the large-scale formation of ACNTs bundles. 相似文献
9.
采用化学气相沉积(CVD)法在碳纤维(CF)表面原位生长碳纳米管(CNTs)。考察了不同催化剂、沉积温度、氢气流量以及样品距进气口距离等工艺参数对CNTs-CF生长的影响。利用SEM和高分辨透射电子显微镜(HRTEM)对CNTs-CF形貌和微结构进行了表征和分析。结果表明:在CF表面原位生长的CNTs为多壁结构,其中以Ni为催化剂得到的CNTs直径小、分布均匀;在600~750℃温度范围内,随着温度的升高,CNTs直径和长度减小,产量降低;随着氢气流量的增加,CNTs直径和长度均增加;距进气口30cm,在CF表面得到的CNTs覆盖率高、直径小且分布窄,有利于制备高质量CNTs。 相似文献
10.
A magnetic composite of multiwalls carbon nanotubes (MWNTs) decorated with Cobalt nanoparticles was synthesized successfully by a simple chemical precipitation and deoxidization method. The composite was analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The pattern of XRD indicated that MWNTs and Cobalt nanoparticles coexisted in the composite. The TEM images revealed that the Cobalt nanoparticles were distributed on the surface of the MWNTs, with the size ranging from 5 to 15 nm. The hysteresis loops of the decorated MWNTs were measured by a vibrating sample magnetometer (VSM), the ferromagnetic signature emerged with the saturated magnetization of 5.8 emu/g, and the coercive of 310 Oe. 相似文献
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Ibrahim I Bachmatiuk A Warner JH Büchner B Cuniberti G Rümmeli MH 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(13):1973-1992
Single-walled carbon nanotubes (SWCNTs) have attractive electrical and physical properties, which make them very promising for use in various applications. For some applications however, in particular those involving electronics, SWCNTs need to be synthesized with a high degree of control with respect to yield, length, alignment, diameter, and chirality. With this in mind, a great deal of effort is being directed to the precision control of vertically and horizontally aligned nanotubes. In this review the focus is on the latter, horizontally aligned tubes grown by chemical vapor deposition (CVD). The reader is provided with an in-depth review of the established vapor deposition orientation techniques. Detailed discussions on the characterization routes, growth parameters, and growth mechanisms are also provided. 相似文献
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《Journal of Experimental Nanoscience》2013,8(5):464-472
The smooth surface of the amorphous Al2O3 film on either silicon or quartz, coated by atomic layer deposition (ALD), was changed to rough surface by annealing in either air or hydrogen at high temperature (745°C) due to the formation of nanosized pinholes and micrometre pimples during the crystallisation of the amorphous Al2O3. The rough surface makes the growth of long carbon nanotubes (CNTs) by chemical vapour deposition impossible. Nevertheless, we were able to develop new catalyst recipes for successful growth of vertically aligned CNTs on ALD-Al2O3 coated silicon and quartz substrates. The lengths of the CNTs reached 90?µm on silicon substrates and 180?µm on quartz substrates. Furthermore, it is observed that the adhesion of CNTs on silicon substrates is much stronger than that on quartz substrates. 相似文献
17.
Hang Q Maschmann MR Fisher TS Janes DB 《Small (Weinheim an der Bergstrasse, Germany)》2007,3(7):1266-1271
The development of assemblies consisting of unencapsulated, sub-10-nm gold particles attached to individual carbon nanotubes (CNTs) with diameters of 2 nm is described. The assemblies are formed on the surface of a porous anodic alumina (PAA) template on which the CNTs (single- or double-walled) are grown by plasma-enhanced chemical vapor deposition. The Au nanoparticles are formed through an indirect evaporation technique using a silicon nitride membrane mask, and diffuse along the PAA surface into the regions containing CNTs. The nanoparticles bind relatively strongly to the CNTs, as indicated by observations of nanoparticles that are suspended over pores or that move along with the CNTs. This approach may provide a new method to functionalize CNTs for chemical or biological sensing and fundamental studies of nanoscale contacts to CNTs. 相似文献
18.
Carbon nanotubes are one of the most intensively explored nanostructured materials. In particular, carbon nanotubes are unique and ideal templates onto which to immobilize nanoparticles allowing the construction of designed nanoarchitectures that are extremely attractive as supports for heterogeneous catalysts, for use in fuel cells, and in related technologies that exploit the inherent 'smallness' and hollow characteristics of the nanoparticles. Here we overview the recent developments in this area by exploring the various techniques in which nanotubes can be functionalized with metals and other nanoparticles and explore the diverse applications of the resulting materials. 相似文献
19.
Dong Liu Yanxiong Liu Guannan Liu 《Fullerenes, Nanotubes and Carbon Nanostructures》2018,26(3):168-174
The influences of carbon nanotubes (CNTs) additions on the flash ignition characteristics of Iron (Fe) and aluminum (Al) nanoparticles (NPs) were presented. CNTs can be used as the additive to these metal nanoparticles for improving the flash ignition and burning processes. Different mass fractions of CNTs additions were considered. The mixture of Al and CNTs could combust in air with obvious giant flame, whereas the mixture of Fe and CNTs combusted under a relative stable condition with slight red light. The temperature distributions were measured using non-contact optical method and showed that Al NPs mixed with CNTs were burning at a higher temperature level than Fe NPs. Although different mass fractions of CNTs cannot significantly change the overall flash ignition phenomenon, CNTs additions influenced the minimum ignition energy (MIE) of mixtures. The appropriate content of CNTs addition can decrease the Fe NPs MIE significantly. However, the Al NPs MIE decreased all along with the increase of CNTs content. The micro- and nano- structures of Fe and Al NPs with CNTs additions before and after ignitions were examined by scanning electron microscope and high-resolution transmission electron microscopy. It was found that the special thermal conductive characteristics of CNTs and the cross-connected features for metal particles with CNTs caused the enhancement of flash ignition. 相似文献