The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The thermal decomposition of ferrocene combined with a catalyst-assisted structuring of a Si-substrate surface is a favourable way to produce Fe-filled carbon nanotubes in good quality and in high yields. In this work we have studied the growth of such aligned filled nanotubes on iron and cobalt pre-coated Si-substrates and their dependence on the deposition time. The nanotube diameter depends on...
Product distributions in the pyrolysis of ethylene, acetylene, and propylene are studied to obtain an experimental database for a detailed kinetic modeling of gas phase reactions in chemical vapor deposition of carbon from these light hydrocarbons. Experiments were performed with a vertical flow reactor at 900°C and pressures from 2 to 15kPa. Gas phase components were analyzed by both on-line and...
Hydrocarbon CVD synthesis of carbon nanotubes (CNTs) is not well understood because it does not follow intuitive gas phase kinetics. Consequently, progress towards industrialization of CNT synthesis has been arduously slow. However, an intuitive understanding of the CNT CVD process can be gained through understanding of the chemistry of free radical condensates that are produced during the pyrolysis...
The influence of the reaction atmosphere on the type of single-walled carbon nanotubes (SWNT) grown during chemical vapor deposition (CVD) was investigated. Methane decomposition was catalyzed by Fe/MgO and Fe–Mo/MgO catalysts in argon, nitrogen and their mixtures. Nitrogen influences the carbon species significantly. The aggregation of iron nanoparticles in nitrogen results in the growth of N-doped...
Carbon nanotubes were synthesized directly by thermal chemical vapor deposition onto the surface of micron-sized metallic fibers to improve the filtration performance of a conventional metal filter. Depending on the synthesis conditions, carbon nanotubes grew up to consist of microstructures like bushes surrounding the metal fibers or like webs crossing between the fibers. The carbon nanotubes grown...
Carbon nanotip arrays were grown from carbon films deposited on silicon substrates by plasma-enhanced hot filament chemical vapor deposition. The carbon films were characterized by the atomic force microscopy and micro-Raman spectrometry and the carbon nanotip arrays were investigated by micro-Raman spectrometry, scanning electron microscopy and X-ray photon spectroscopy. The results indicate that...
This paper presents, for the first time, a semi-quantitative study on the production of densely packed and vertically aligned (DPVA) single-walled carbon nanotubes (SWNTs) from ultra-thin catalytic films. An up-to-date highest volume density (60–70kgm −3 ) and the corresponding high surface density on the order of 10 16 m −2 of DPVA-SWNTs have been achieved by point-arc microwave...
Nitrogen molecules have been encapsulated into the central hollows of vertically aligned carbon nitride (CN) multiwalled nanofibers by dc plasma-enhanced chemical vapor deposition with C 2 H 2 , NH 3 , and N 2 gases on a Ni/TiN/Si(100) substrate at 650°C. X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectra showed the existence of nitrogen...
Single-walled carbon nanotubes (SWNTs) are successfully grown on magnesite crystal by pyrolysis of methane gas under moderate conditions, demonstrating the possibility of naturally occurring SWNTs.The obtained SWNTs were analyzed by Raman scattering, transmission electron microscope (TEM), and thermogravimetric (TG) measurements. These measurements revealed that high purity SWNTs having diameters...
Platelet graphite nanofibers are materials produced from the decomposition of carbon monoxide and hydrogen over iron powders. The surface consists of terminated graphite edges, differing from traditional graphite materials in which basal plane graphite surfaces dominate. The 3-dimensional morphology and crystal face exposure on the nanofiber surface was determined by selected area electron diffraction...
The floating catalyst (FC) method for synthesis of single- and multi-wall carbon nanotubes was optimized and scaled up to yield 6g/h and 20g/h of products, respectively. Different CNTs purification methods were compared. It was found that the procedure involving room temperature bromination is the most effective to purify the FC-CNTs. The hydrogen up-take capacities of the different products were...
Centimeter-size multi-branched tree-like carbon structures have been generated by the catalytic chemical vapor deposition of toluene using ferrocene as the catalyst precursor and investigated by means of SEM, TEM, and EDX. It is found that a temperature of 1000–1200°C and a carrier gas flow rate of 1000–2500ml/min are necessary for the generation of the carbon trees. Their morphologies and microstructures...
Iron carbide–oxide filled carbon nanotubes and nanocapsules (CNCs) are separately synthesized by catalytic chemical vapor deposition of coal gas at 950°C with ferrocene as catalyst. The products are examined using transmission electron microscopy and XRD techniques, showing that nanosized iron carbide–oxide particles are encapsulated by well ordered carbon layers. Magnetic moment measurement reveals...
Inspired by a special biological structure in nature, a kind of urchin-like nano/micro hybrid design was proposed to modify conventional micrometer-sized electroactive materials for lithium ion battery (LIB). By catalytic chemical vapor deposition to in situ grow carbon nanofibers on the surface of natural graphite spheres, we fabricated the nano/micro hybrid composite with an urchin-like structure...
Recent discovery of enhanced field emission current intensity from arrays of bundles of carbon nanotubes (CNT) has prompted this investigation of the growth of CNT bundle arrays by metal-catalyzed chemical vapor deposition (CVD), in order to understand and control the growth of these arrays. CNT bundle array growth has been characterized as a function of array geometric parameters: the CNT bundle...
Pyrolytic carbon layers were deposited from methane/oxygen/argon mixtures on planar substrates (silicon wafers) at a total pressure of 100kPa, a maximum gas residence time of 2s and a temperature of 1100°C. The depositions were performed in a hot-wall reactor with the substrate oriented parallel to the gas flow. Particular attention was paid to factors that influence the reproducibility of the deposited...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.