scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Alloy hydride catalyst route for the synthesis of single-walled carbon nanotubes, multi-walled carbon nanotubes and magnetic metal-filled multi-walled carbon nanotubes

14 Nov 2006-Nanotechnology (IOP Publishing)-Vol. 17, Iss: 21, pp 5299-5305
TL;DR: In this article, a single-step technique for the synthesis of single-walled carbon nanotubes (SWNTs), multilayer carbon nanostructures (MWNTs) and magnetic metal-filled MWNTs using a fixed bed reaction thermal chemical vapour deposition (CVD) using alloy hydride catalyst is presented.
Abstract: This paper presents a novel, cost-effective and single-step technique for the synthesis of single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs) and magnetic metal-filled MWNTs using a fixed bed reaction thermal chemical vapour deposition (CVD) using alloy hydride catalyst. The single-step method involves the pyrolysis of methane at suitable temperatures over fine powders of certain Mischmetal-based AB3 alloy hydride catalysts, prepared through the hydrogen decrepitation technique. These carbon nanostructures have been characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray analysis (EDAX), thermo-gravimetric analysis (TGA) and Raman spectroscopy. The magnetic properties of these metal-filled MWNTs have been studied by vibrating sample magnetometry, and the results are discussed.
Citations
More filters
Journal ArticleDOI
TL;DR: In this article, a novel way of synthesizing graphene-carbon nanotube hybrid nanostructure as an anode for lithium ion batteries was proposed, which was obtained by homogeneous mixing of chemically modified graphene and carbon nanotubes constituents.
Abstract: We report a novel way of synthesizing graphene-carbon nanotube hybrid nanostructure as an anode for lithium (Li) ion batteries. For this, graphene was prepared by the solar exfoliation of graphite oxide, while multiwalled carbon nanotubes (MWNTs) were prepared by the chemical vapor deposition method. The graphene–MWNT hybrid nanostructure was synthesized by first modifying graphene surface using a cationic polyelectrolyte and MWNT surface with acid functionalization. The hybrid structure was obtained by homogeneous mixing of chemically modified graphene and MWNT constituents. This hybrid nanostructure exhibits higher specific capacity and cyclic stability. The strengthened electrostatic interaction between the positively charged surface of graphene sheets and the negatively charged surface of MWNTs prevents the restacking of graphene sheets that provides a highly accessible area and short diffusion path length for Li-ions. The higher electrical conductivity of MWNTs promotes an easier movement of the electrons within the electrode. The present synthesis scheme recommends a new pathway for large-scale production of novel hybrid carbon nanomaterials for energy storage applications and underlines the importance of preparation routes followed for synthesizing nanomaterials.

253 citations

Journal ArticleDOI
TL;DR: In this article, a multiscale analysis from the delicate catalyst control needed at the atomic level, CNT agglomerate formation at the mesoscopic scale, to the continuous mass production process on the macroscopic scale was reviewed by a multi-scale analysis.

159 citations


Cites methods from "Alloy hydride catalyst route for th..."

  • ...Various reactors, including fixed beds [63,64], floating catalyst process with a low solid density [65– 68], and fluidized beds [17,24,63,69–79] were used to produce CNTs on a large scale....

    [...]

Journal ArticleDOI
TL;DR: This work demonstrates a considerable improvement in performance compared to existing cathode electrocatalysts being used in PEMFC and can be extended to the synthesis of metal, metal oxides or metal alloy nanoparticle decorated nitrogen doped carbon nanostructures for various electrochemical energy applications.
Abstract: The efforts to push proton exchange membrane fuel cells (PEMFC) for commercial applications are being undertaken globally. In PEMFC, the sluggish kinetics of oxygen reduction reactions (ORR) at the cathode can be improved by the alloying of platinum with 3d-transition metals (TM = Fe, Co, etc.) and with nitrogen doping, and in the present work we have combined both of these aspects. We describe a facile method for the synthesis of a nitrogen doped (reduced graphene oxide (rGO)–multiwalled carbon nanotubes (MWNTs)) hybrid structure (N–(G–MWNTs)) by the uniform coating of a nitrogen containing polymer over the surface of the hybrid structure (positively surface charged rGO–negatively surface charged MWNTs) followed by the pyrolysis of these (rGO–MWNTs) hybrid structure–polymer composites. The N–(G–MWNTs) hybrid structure is used as a catalyst support for the dispersion of platinum (Pt), platinum–iron (Pt3Fe) and platinum–cobalt (Pt3Co) alloy nanoparticles. The PEMFC performances of Pt–TM alloy nanoparticle dispersed N–(G–MWNTs) hybrid structure electrocatalysts are 5.0 times higher than that of commercial Pt–C electrocatalysts along with very good stability under acidic environment conditions. This work demonstrates a considerable improvement in performance compared to existing cathode electrocatalysts being used in PEMFC and can be extended to the synthesis of metal, metal oxides or metal alloy nanoparticle decorated nitrogen doped carbon nanostructures for various electrochemical energy applications.

140 citations

Journal ArticleDOI
TL;DR: In this article, the effect of a longitudinal magnetic field on the transverse vibration of a magnetically sensitive double-walled carbon nanotube (DWCNT) was studied based on nonlocal elasticity theory.

139 citations


Cites methods from "Alloy hydride catalyst route for th..."

  • ...[8] considered metal-filled multi-walled nanotubes and studied their magnetic properties by using vibrating sample magnetometry....

    [...]

Journal ArticleDOI
TL;DR: In this article, a solution-free green method using focused solar electromagnetic radiation is used to synthesize graphene and graphene-multiwalled carbon nanotube (MWNT) composite.
Abstract: A solution-free green method using focused solar electromagnetic radiation is used to synthesize graphene and graphene–multiwalled carbon nanotube (MWNT) composite. Stable nanofluids are prepared by dispersing the nanomaterials in polar base fluids. Thermal conductivity of the nanofluids improves with graphene–MWNT nanocomposites as additives, which could be due to prevention of restacking of graphene sheets by MWNT along with a synergistic effect of intrinsic high thermal conductivity of graphene and MWNT. The advantage of the present synthesis method in particular to nanofluids application is that the presence of oxygen functional groups resulting from pre-functionalized MWNT rules out the need for functionalizing the hybrid composite again, thereby preserving the high thermal properties of graphene. Thermal conductivity enhancement of 9.2% and 10.5% is obtained with graphene and graphene–MWNT nanofluids in de-ionized water at room temperature for 0.04% volume fraction. The high thermal transport characteristics of graphene–MWNT composite nanofluids is ascribed to the high aspect ratio of MWNT and graphene, which in turn can form tightly bonded clusters and, by suppressing the interface resistance, can become excellent additives to attain high thermal conductivity. Further, an enhancement in heat-transfer coefficient of 193% at Reynolds number 2000 for 0.02% volume fraction of aqueous graphene–MWNT nanofluids suggests the potential application of the present hybrid material-based nanofluids in cooling circuits.

130 citations

References
More filters
Journal ArticleDOI
Sumio Iijima1
01 Nov 1991-Nature
TL;DR: Iijima et al. as mentioned in this paper reported the preparation of a new type of finite carbon structure consisting of needle-like tubes, which were produced using an arc-discharge evaporation method similar to that used for fullerene synthesis.
Abstract: THE synthesis of molecular carbon structures in the form of C60 and other fullerenes1 has stimulated intense interest in the structures accessible to graphitic carbon sheets. Here I report the preparation of a new type of finite carbon structure consisting of needle-like tubes. Produced using an arc-discharge evaporation method similar to that used for fullerene synthesis, the needles grow at the negative end of the electrode used for the arc discharge. Electron microscopy reveals that each needle comprises coaxial tubes of graphitic sheets, ranging in number from 2 up to about 50. On each tube the carbon-atom hexagons are arranged in a helical fashion about the needle axis. The helical pitch varies from needle to needle and from tube to tube within a single needle. It appears that this helical structure may aid the growth process. The formation of these needles, ranging from a few to a few tens of nanometres in diameter, suggests that engineering of carbon structures should be possible on scales considerably greater than those relevant to the fullerenes. On 7 November 1991, Sumio Iijima announced in Nature the preparation of nanometre-size, needle-like tubes of carbon — now familiar as 'nanotubes'. Used in microelectronic circuitry and microscopy, and as a tool to test quantum mechanics and model biological systems, nanotubes seem to have unlimited potential.

39,086 citations

Journal ArticleDOI
Sumio Iijima1, Toshinari Ichihashi1
17 Jun 1993-Nature
TL;DR: In this article, the authors reported the synthesis of abundant single-shell tubes with diameters of about one nanometre, whereas the multi-shell nanotubes are formed on the carbon cathode.
Abstract: CARBON nanotubes1 are expected to have a wide variety of interesting properties. Capillarity in open tubes has already been demonstrated2–5, while predictions regarding their electronic structure6–8 and mechanical strength9 remain to be tested. To examine the properties of these structures, one needs tubes with well defined morphologies, length, thickness and a number of concentric shells; but the normal carbon-arc synthesis10,11 yields a range of tube types. In particular, most calculations have been concerned with single-shell tubes, whereas the carbon-arc synthesis produces almost entirely multi-shell tubes. Here we report the synthesis of abundant single-shell tubes with diameters of about one nanometre. Whereas the multi-shell nanotubes are formed on the carbon cathode, these single-shell tubes grow in the gas phase. Electron diffraction from a single tube allows us to confirm the helical arrangement of carbon hexagons deduced previously for multi-shell tubes1.

8,018 citations

Journal ArticleDOI
Donald S. Bethune1, C. H. Klang1, M.S. de Vries1, G. Gorman1, R. Savoy1, J. E. Vazquez1, Robert Beyers1 
17 Jun 1993-Nature
TL;DR: In this paper, it was shown that covaporizing carbon and cobalt in an arc generator leads to the formation of carbon nanotubes which all have very small diameters (about 1.2 nm) and walls only a single atomic layer thick.
Abstract: CARBON exhibits a unique ability to form a wide range of structures. In an inert atmosphere it condenses to form hollow, spheroidal fullerenes. Carbon deposited on the hot tip of the cathode of the arc-discharge apparatus used for bulk fullerene synthesis will form nested graphitic tubes and polyhedral particles. Electron irradiation of these nanotubes and polyhedra transforms them into nearly spherical carbon 'onions'. We now report that covaporizing carbon and cobalt in an arc generator leads to the formation of carbon nanotubes which all have very small diameters (about 1.2 nm) and walls only a single atomic layer thick. The tubes form a web-like deposit woven through the fullerene-containing soot, giving it a rubbery texture. The uniformity and single-layer structure of these nanotubes should make it possible to test their properties against theoretical predictions.

3,758 citations

Book
01 Jan 1949
TL;DR: In this paper, the authors present an X-ray analysis of metallic materials and their properties, such as elastic properties, damping capacity and shape memory alloys, as well as their properties of metal and alloys.
Abstract: General physical and chemical constants X-ray analysis of metallic material Crystallography Crystal chemistry Metallurgically important minerals Thermochemical data Physical properties of molton salts Metallography Equilibrium diagrams Gas-metal systems Diffusion in metals General physical properties Elastic properties, damping capacity and shape memory alloys Temperature measurement and thermoelectric properties Radiating properties of metals Electron emission Electrical properties Magnetic materials and their properties Mechanical testing Mechanical properties of metals and alloys Sintered materials Lubricants Friction and wear Casting alloys and foundry data Engineering ceramics and refractory materials Fuels Heat treatment Metal cutting and forming Corrosion Electroplating and metal finishing Welding Soldering and brazing Vapour deposited coatings and thermal spraying Superplasticity Metal-matrix composites Non-conventional and emerging metallic minerals modelling and simulation supporting technologies for the processing of metals and alloys.

3,593 citations

Journal ArticleDOI

3,052 citations