Papers by Keyword: Carbon Nanostructures

Abstract: In this paper we have considered two versions of elementary cells for creating a nanomembrane, which will be used to separate natural gas into different gas components. Calculated trajectories of helium atoms and methane molecules interacting with elementary structural units of the membrane are presented. The model is based on a discrete approach to describe the interaction of a structure with atoms and molecules.

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.

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.

Abstract: Graphene, because of its exceptional properties such as very good electrical conductance, flexibility and high optical transparency in visible light spectrum, has proved to be an excellent nanomaterial for modern electronic applications. The natural point of view is to use this new nanomaterial for the development of unique textronic devices such as sensory systems for monitoring human body’s vital functions and atmospheric composition. The present review shows the state of art of materials science and possibilities of the smart textiles design with graphene. The most promising applications of graphene for the design of textronic devices are the development of conductive polymer composites (CPC) and the development of inks and pastes for printing conductive tracks on textile materials. The preliminary results of implementation of 2D carbon structure into textronic devices are presented.

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.

Abstract: Carbon nanotubes were produced from the aerosol-assisted catalytic CVD method using palm oil as the precursor and ferrocene as the catalyst. The CNTs were yielded at optimized temperature of 700oC and the Field Emission Scanning Electron Microscope showed the image of CNTs produced. Raman Spectroscopy, energy dispersive X-ray and Thermogravimetric Analysis were then used to further study the Raman Spectra, purity and identification of samples.

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.

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.

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.

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.