Papers by Keyword: Carbon Nanostructures

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Authors: Hong Dan Zhang, Xiao Ping Zou, Jin Cheng, Fei Li, Peng Fei Ren
Abstract: Carbon nanotubes and carbon nanowires were synthesized by ethanol catalytic combustion (ECC) technique, using FeCl3 solution as a catalyst precursor. Applying the 0.01 mol/l, 0.1 mol/l and 1 mol/l FeCl3 as catalyst precursor solution to the copper plate, carbon nanotubes and carbon nanowires were synthesized. The effect of concentration on growth and structural changes of the as-grown nanomaterials are illustrated and discussed. This technique has advantages of low cost, large scale production and flexible reaction conditions, etc. This technique can be used to synthesize carbon nanotubes and nanowires on metal substrate directly. This technique also has potential applications for fabricating nano-electrical devices.
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Authors: Marco Vittori Antisari, Daniele Mirabile Gattia, L. Brandão, Renzo Marazzi, Amelia Montone
Abstract: Carbon nanostructures are under deep investigation due their peculiar properties and possible applications. In particular, development of new methods for the synthesis of these materials and their mechanism of formation represent interesting research fields. Arc discharge allows to produce different forms of carbon nanostructures. The parameters involved in the process, voltage, current density, type and pressure of the surrounding gas can be controlled especially for achieving high quantity of material with enhanced characteristics in terms of purity while the use of transition metal-graphite mixtures has been used to produce single wall structures. Moreover direct current (DC) and alternating current (AC) are suitable for producing carbon nano-materials, but different results can be obtained. In this work the effect of the power frequency in an AC arc discharge technique on the synthesis of carbon nanostructures is reported. Pure graphite electrodes have been arched in air in an homemade apparatus where the material can be collected directly on a cylindrical collector fixed near the arc. In order to avoid the formation of deposits under the arc a symmetrical configuration of the electrodes has been set. The production of carbon soot containing Single Wall Nanohorns (SWNH) and highly convoluted graphene sheets is optimized. The range of power frequencies 32-1000Hz has been investigated and the arcs have been ignited fixing the voltage at 28 V. The materials has been analyzed by field emission scanning electron microscope and high resolution transmission electron microscope. The microstructure of the material synthesized by this apparatus is affected by the power frequency, as the experimental results demonstrate. The samples produced at low frequency presented high amounts of single wall structures, SWNH-type. More compact structures, similar to large onion-like structures, have been found in samples synthesized at high frequency values.
1766
Authors: Suhufa Alfarisa, Suriani Abu Bakar, Azmi Mohamed, Norhayati Hashim, Azlan Kamari, Illyas Md Isa, Mohamad Hafiz Mamat, Abdul Rahman Mohamed, Mohamad Rusop Mahmood
Abstract: Research innovation in finding new carbon sources for carbon nanostructures material production was intensively done lately. In this review, we present the production of carbon nanostructures such as carbon fibers, nanotubes, nanowhiskers, microspheres and porous carbon from several waste materials. The benefit of the use of waste materials such as waste cooking palm oil, chicken fat, waste natural oil, glycerol, printed circuit board, plastic wastes, waste engine oil, scrap tyre, heavy oil residue and deoiled asphalt is not only in the term of their environmentally friendly approach but also the economic value to reduce the high cost of carbon material production using common sources. On the other hand, these materials are easy access sources and can be alternative utilization to convert waste materials into high value nanomaterials.
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Authors: Suhufa Alfarisa, Suriani Abu Bakar, Azmi Mohamed, Norhayati Hashim, Azlan Kamari, Illyas Md Isa, Mohamad Hafiz Mamat, Abdul Rahman Mohamed, Mohamad Rusop Mahmood
Abstract: Research innovation in finding new carbon sources for carbon nanostructured material production was intensively done lately. In this review, we present the production of carbon nanostructures such as carbon fibers, nanotubes, nanowhiskers, microspheres and porous carbon from several waste materials. The benefit of the use of waste materials such as waste cooking palm oil, chicken fat, waste natural oil, glycerol, printed circuit board, plastic wastes, waste engine oil, scrap tyre, heavy oil residue and deoiled asphalt is not only in the term of their environmentally friendly approach but also the economic value to reduce the high cost of carbon material production using common sources. On the other hand, these materials are easy access sources and can be alternative utilization to convert waste materials into high value nanomaterials.
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Authors: Gabriela Borin Barin, Thalita Santos Bispo, Iara de Fátima Giminenez, Ledjane Silva Barreto
Abstract: Brazil has a large potential for energy generation and development of new materials from renewable resources through eco-friendly routes, which presents an alternative for construction of an eco-technological platform, where the entire lifecycle of the material or industrial product be sustainable. The proposal of the present work was synthesize carbon nanostructures from coconut coir dust and via template synthesis mediated by layered clays through hydrothermal process. The obtained materials were characterized by Raman Spectroscopy, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscope (SEM). Carbon phase formation was indicated by infrared results with bands at 1444 cm-1 and 1512 cm-1 assigned to C=C of aromatic groups. Raman spectroscopy results showed presence of carbonaceous species by the appearance of D and G bands assigned to disordered and graphitic crystallites, respectively. SEM results showed overlapping sheets and plates formation. High Resolution Transmission Electron Microscopy measures are in progress.
1355
Authors: Kyu Suk Han, Tae Gyung Ko
Abstract: We report the observation of the carbon nanostructures simply obtained from the sol-gel process using zirconium alkoxide with subsequent heat-treatment. A Raman study showed that the well-defined D and G active modes in multi-walled carbon nanotube similarly appeared in the sample prepared at 350  and 400 . Those disappeared when the sample was heat-treated above 450 , at which its phase fully transformed to zirconia. We observed through HRTEM that either sphere or tube-like carbon nanostructure appeared dispersedly or in a cluster among the oxide aggregates at 350  and 400 . Our study demonstrated that both of the two carbon nanostructures occurred in an intermediate related to carbonization, which may exist during the heat-treatment even in air
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Authors: Hong Mei Zhu, Shu Mei Lei, Tong Chun Kuang
Abstract: In this paper, a low carbon steel was used as the substrate to prepare the carbon nanostructural materials by the oxygen-acetylene flame method. The experimental results show that the composite products including nodular carbon nanoparticles and amorphous carbon were obtained on the substrate after a mechanical polishing pretreatment. Comparatively, the short tubular carbon nanofibers with the diameter of around 100 nm were deposited on the substrate pretreated by dipping in the concentrated nitric acid solution. The possible mechanism for the growth of such carbon nanofibers was discussed.
2269
Authors: Malay Jana, Anjan Sil, Subrata Ray
Abstract: Different types of carbon nanostructure materials have been grown on nano-sized transition metal oxide based catalyst particles by catalytic chemical vapour deposition. The present investigation reveals an important role of melting or surface melting of oxide catalysts for the growth of carbon nanostructure materials. In the reducing environment prevailing during the growth of nanostructures, oxide catalysts are reduced to metals, which may act as a template for the growth of carbon nanostructure materials. Flow rate of acetylene gas is crucial in catalyzing the growth, as high flow rate of acetylene may cover the catalyst particles with a layer of decomposed carbon, rendering the particles incapable of playing the role of catalyst. The size of the catalyst and the extent of melting, determined primarily by the extent of doping, are important in deciding whether the conditions are favourable for the growth of multi walled carbon nanotube, nanofiber or other nanostructures. Smaller particle size and low doping level favour the growth of multi walled carbon nanotube while growth of nanofiber is commonly observed with larger particles and higher doping level. The size (i.e. diameter) of the nanostructures growing around the catalyst is proportional to the particle size of the catalyst.
159
Authors: Claudia Scilletta, Marco Servidori, L. Barba, E. Cappelli, S. Orlando, P. Ascarelli
Abstract: The physical properties of graphene nano-structures are highly anisotropic and generally correlated to the graphene sheet orientation. We investigated the capability to grow nano-graphene structured carbon films and to control their texturing by pulsed laser ablation of a pyrolytic graphite target (Nd:YAG laser, 2nd harmonic: λ=532 nm, hν=2.33 eV, τ=7 ns, ν=10 Hz, φ=7 J/cm2), operating at different temperature conditions. Carbon films were deposited on Si <100> substrates. Detailed characterisation by synchrotron X-ray measurements were performed on samples deposited in vacuum (~10-3 Pa) at high substrate temperatures (>800°C) and at room temperature followed by post-annealing at high temperature (>800°C). The X-ray measurements established the formation of nano-sized graphene structures for both sample sets. In the first set, the nano-particles are correlated among them, their size increases with substrate temperature and a longitudinal growth of parallel graphene layers occurs, with the ˆc axis parallel to the substrate. In post annealed sample set, on the contrary, the nano-particles size is smaller and depends weakly on annealing temperature. The graphene ˆc axis results to be randomly oriented up to ~850°C. Above this temperature it seems that a transition phase occurs and the c axis results to lie parallel to substrate plane.
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Authors: A. Mangione, Lorenzo Torrisi, A. Picciotto, Anna Maria Visco, Nino Campo
Abstract: Damond-like (DLC) films can be produced by Pulsed Laser Deposition (PLD) technique. Different pulsed lasers can be employed to generate hot carbon plasma, to deposit and/or to implant energetic carbon atoms and molecules on substrates. A Nd:Yag laser radiation with ns pulse duration, about 1010 W/cm2intensity and 30 Hz repetition rate, can be employed to produce in vacuum thin carbon films with properties similar to graphite and diamond. The films were deposited on SiO2 substrates, placed at different distances and angles from the target. The PLDgenerated plasma can be controlled “in situ” by mass quadrupole spectroscopy and time-of-flight tehniques. “Ex situ” investigations were performed on the deposited films by using the Scanning Electron Microscopy (SEM) and Raman spectroscopy. Deposited films show evidence of carbon nanostructures, which find a growing variety of applications in medicine and bio-enegineering fields. Diamond-like carbon (DLC) shows low friction, high atomic density, hard but flexible structure, chemical inertia, wear, diffusion and corrosion resistance and highly bio and hemocompatible properties.
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