Synthesis of Carbon Nanostructures in a Plasma Jet Reactor (original) (raw)
Related papers
Formation of carbon nanostructures by the plasma jets: synthesis, characterization, application
Materials Today: Proceedings, 2018
Carbon nanostructures were synthesized without the use of catalysts by the conversion of hydrocarbons in the DC plasma jet system. The samples of carbon nanotubes, nanofibers, graphene, onion like structures have been characterized by electron microscopy, thermal analysis, Raman spectroscopy. An experimental study of the composition of the gas phase with variation of the type of the plasma-forming gas and the type of carbon source was carried out. The synthesized samples have been used in the composition of the functional ceramic and in electrochemical systems.
Synthesis of carbon nanostructures by using thermal plasma torch
Brazilian journal of …, 2004
Some recent results concerning the synthesis of carbon nanostructures in a thermal plasma generating by a plasma torch are presented. Several tests were carried out in different operational conditions. The plasma was formed with argon and different gas mixtures of argon-acetylene or argon-methane to which some catalyst materials (ferrocene and cerium oxide) were added. These catalysts were introduced into the plasma in a solid (powder) or/and a gaseous state. Their feeding rate into the plasma jet was fixed along with some other operating conditions such as plasma power, gas flow rate and reactor pressure. The principal main feature observed was a short reaction time so that each test lasted for no longer than 5 minutes. The solid products obtained were collected and prepared for following analyses. The products were examined using XRD and TEM techniques in order to characterize the morphological structure of their samples. The spatial distribution of temperature in the plasma was evaluated by in-situ emission spectroscopy. The self-absorption was taken into account by simulating an integrated radiation in relation to the Swan band d3Pg ® a3Pu(0,0), emitted by the C2 radical. Also, the exhaust gases were characterized by gas chromatography during each test.
Plasma Chemistry and Plasma Processing, 2020
Wide spectrum of carbon nanostructures was synthesized by means of simple plasma chemistry using DC plasma torch: carbon nanotubes, nanowalls, graphene, hydrogenated graphene and a mixture of nanotubes with graphene. The synthesis was performed in the plasma-chemical reactor under the pressure varying in the close range 350-710 Torr with different types of hydrocarbon as an admixture to the helium plasma. Aliphatics (propane, butane methane and acetylene) were used providing a variation of C:H ratio. The plasmachemical pyrolysis of hydrocarbons in the temperature range 1000-8000 K was analyzed using the thermodynamic and gas dynamic characteristics. It is determined that the main contribution to the formation of predecessors of solid carbon makes the composition of plasma jet in the temperature range 2500-3500 K. In this range the interrelation between atomic hydrogen H and hydrocarbon molecules CH varies dramatically, and the mole fraction of solid carbon Cgr goes upward. The C:H ratio in the carbon feedstock is shown to have an influence on the particularity of processes of formation of condensed carbon.
Green Applications of Carbon Nanostructures produced by Plasma Techniques
MRS Advances
The study of several types of plasma reactors used to obtain carbon nanostructures (CNS) is realized in the Laboratory of Plasma Applications. To obtain carbon nanotubes (CNT) thermal plasma was used and carbon nanofibers (CNF) were obtained with glow discharge. Optical emission spectroscopy was applied to correlate some plasma parameters with CNS growth. Several analytical techniques are used to study CNS obtained by both plasma techniques. In this work, we present results concerning the use of CNS as harmful gases traps and some results of a CNT based supercapacitor prototype are also depicted. Experimental results here detailed, show the capacity of CNF to absorb nitrogen oxides (NOx), sulfur dioxide (SO2) and, at less proportion, carbon dioxide (CO2). CNF films were obtained by electrophoretic deposition technique and by adding CNT ink; preliminary results showed a capacitance value of 2.69 F/g. This value remains still low compared to some supercapacitors, therefore additional ...
Fast nanostructured carbon microparticle synthesis by one-step high-flux plasma processing
Carbon
This study demonstrates a fast one-step synthesis method for nanostructured carbon microparticles on graphite samples using high-flux plasma exposure. These structures are considered as potential candidates for energy applications such as Li-ion batteries and supercapacitors. The samples were exposed to plasmas in the linear plasma generator Pilot-PSI with an average hydrogen ion-flux of ~10 24 m-2 s-1. The parameter window was mapped by varying the ion energy and flux, and surface temperature. The particle growth depended mainly on the sample gross-erosion and the resulting hydrocarbon concentration in the plasma. A minimum concentration was necessary to initiate particle formation. The surface of the sample was covered with microparticles with an average growth rate of 0.2 μm/s, which is significantly faster than most chemical methods. The particles were initially volumetrically grown in in the gas-phase by a multiphase process and after deposition on the sample their growth proceeded. Scanning and transmission electron microscopy reveal that the core of these microparticles can be made of an
Synthesis of carbon nanomaterials by thermal arc plasma
2005
Different families of carbon nanostructures produced by a continuous plasma process are presented. Due to the flexibility of this original technology, properties of classical carbon black products can be adjusted more freely during synthesis and an even wider range of parameters is
We have performed an experimental analysis on the investigation of intense plasma jet irradiation on Si (100) substrates using a repetitive pulsed capillary discharge (PCD) device operating in methane gas at low pressure. The surface modifications induced by the plasma jet are characterized using standard surface science diagnostic tools, such as scanning electron microscopy (SEM), energy-dispersive x-ray (EDX) analysis and Raman spectroscopy (RS) and the results are reported.
Nanostructured Carbon Growth by an Expanding Radiofrequency Plasma Jet
NATO Science Series II: Mathematics, Physics and Chemistry, 2006
It is about 15 years that the carbon nanotubes have been discovered by Sumio Iijima in a transmission electron microscope. Since that time, these long hollow cylindrical carbon molecules have revealed being remarkable nanostructures for several aspects. They are composed of just one element, Carbon, and are easily produced by several techniques. A nanotube can bend easily but still is very robust. The nanotubes can be manipulated and contacted to external electrodes. Their diameter is in the nanometer range, whereas their length may exceed several micrometers, if not several millimeters. In diameter, the nanotubes behave like molecules with quantized energy levels, while in length, they behave like a crystal with a continuous distribution of momenta. Depending on its exact atomic structure, a single-wall nanotube-that is to say a nanotube composed of just one rolled-up graphene sheet-may be either a metal or a semiconductor. The nanotubes can carry a large electric current, they are also good thermal conductors. It is not surprising, then, that many applications have been proposed for the nanotubes. At the time of writing, one of their most promising applications is their ability to emit electrons when subjected to an external electric field. Carbon nanotubes can do so in normal vacuum conditions with a reasonable voltage threshold, which make them suitable for cold-cathode devices. Nanotubes are also good candidates for the design of composite materials. They can increase the conductivity, either electrical or thermal, of polymer matrices which they are embedded in at a few weight percents, while improving the mechanical resistance of the materials. Most spectacular, but still far from industrialization, is the nanotube-based field-effect transistor. Here, a singlewall semiconducting nanotube, contacted to two electrodes, may block or may transmit an electric current depending on the potential applied to a gate electrode placed at near proximity. Many other applications are foreseen, among which nanoscopic gas sensing in which one property of the nanotube, sensitive to adsorbed molecules, is measured. Gas selectivity may be realized by a suitable functionalization of the nanotubes. Optical and opto-electronic properties of single-wall nanotubes are also promising for infra-red applications. While the list of potential applications increases every month, the basic properties of intrinsic nanotubes are well documented and relatively well understood. Only relatively, because there remain several important open issues. Many-body effects, although predicted to occur in one-dimensional systems since a long time, are not clearly evidenced. Luttinger-liquid behavior, xi for instance, is not fully recognized by experiments on metallic nanotubes. Excitons in semiconducting tubes constitute another topic of recent, sometimes controversial debates. More important, perhaps, the synthesis and growth mechanisms of the carbon nanotubes are not clearly pinned out. It is remarkable that these beautiful molecules can be produced in such many different physical and chemical conditions (electric arc discharge, catalytic chemical vapor deposition, laser ablation ...). Partly due to that, it is still not possible at the time of writing to produce nanotubes with all the same structure in a controllable way. Large-scale, but detailed characterization of the nanotubes, like with any other nanostructures, remains a great experimental challenge that will need to be overcame. Whether or not nanotubes will have important industrial applications is not the essential point for the time being. What can be given for sure is that the carbon nanotubes have triggered an intense research activity thanks to which nanotechnology is developing so fast. The nanotubes are indeed ideal objects to deal with in this context before other nanostructures, perhaps, will supplement them and will open the way to real technological applications. In this book, many aspects of the nanotubes are either touched or described in details. The book is a snapshot, incomplete perhaps, of the state of the art at the time where the ASI took place, on the shore of the Black Sea. We gratefully acknowledge the generous support from the NATO Scientific and Environmental Affairs Division and the University of Namur. We thank all authors for preparing high-quality manuscripts.
Influence of Temperature Profile on the Composition of Condensed Carbon in a Plasma Jet
Journal of Structural Chemistry, 2020
Graphene materials are synthesized in a thermal plasma jet without using size forming catalysts. The synthesis was performed on a direct current plasma torch operating at 28-30 kW with a pressure of 100-710 Torr. The synthesis products are studied by electron microscopy, X-ray diffraction, and dynamic light scattering. It is found that structures formed in the plasma jet have a flake morphology regardless of the type of the carbon bearing source. Thermodynamic calculations testify a correlation between the temperature profile in the plasma jet and the composition of condensed carbon (redistribution between С60 and С80). The application areas of flaky structures are discussed.