Numerical and Experimental Study of the Multichannel Nature of the Synthesis of Carbon Nanostructures in DC Plasma Jets
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Numerical and Experimental Study of the Multichannel Nature of the Synthesis of Carbon Nanostructures in DC Plasma Jets M. B. Shavelkina1 · P. P. Ivanov1 · A. N. Bocharov1 · R. Kh. Amirov1 Received: 27 August 2020 / Accepted: 6 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract 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. Keywords Plasma pyrolysis · Hydrocarbons · Carbon nanostructures · Plasma composition · Thermodynamic analysis
Introduction Carbon nanotubes are stretched objects like hollow cylinders from one up to several tens nanometers in diameter and several microns in length. They combine the properties of molecules and of solid matter and might be considered as an intermediate state of the matter (between the molecular and condensed states). These tubes contain one or several hexagonal graphite layers bended into cylinder [1, 2]. In addition to cylindrical geometry the graphite layer might form a two-dimensional crystal—graphene. Unique physical and mechanical properties of carbon nanotubes and graphene and their high specific surface make them applicable for the development of new electronic devices, ultra resistant and
* A. N. Bocharov [email protected] 1
Joint Institute for High Temperatures of Russian Academy of Sciences, Moscow, Russia
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Plasma Chemistry and Plasma Processing
light materials, advanced power sources (hydrogen storage, supercapacitors, fuel cells, photovoltaic convertors), efficient filters, biocompatible materials and so on [3–5]. Nowadays the catalyst assisted synthesis of carbon nanomaterials in the volume [6] or on the tailor-made substrate [7] is widely spread. Synthesis of carbon nanomaterials might occur in the vacuum [8], in the stationary inert gas [9], in the gas flow [10], in the plasma [11, 12]. Compared to other established synthesis methods, plasma offers control over the growth of carbon nanostructures, with improved physical and chemical
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