Abstract
Synthesis of graphene materials in a plasma stream from an up to 40 kW direct current (DC) plasma torch is investigated. These materials are created by means of the conversion of hydrocarbons under the pressure 350–710 Torr without using catalysts, without additional processes of inter-substrate transfer and the elimination of impurities. Helium and argon are used as plasma-forming gas, propane, butane, methane, and acetylene are used as carbon precursors. Electron microscopy and Raman imaging show that synthesis products represent an assembly of flakes varying in the thickness and the level of deformity. An occurrence of hydrogen in the graphene flakes is discovered by X-ray photoelectron spectroscopy, thermal analysis, and express-gravimetry. Its quantity depends on the type of carrier gas. Quasi-one-dimensional approach under the local thermodynamic equilibrium was used to investigate the evolution of the composition of helium and argon plasma jets with hydrocarbon addition. Hydrogen atoms appear in the hydrogen-rich argon jet under higher temperature. This shows that solid particles live longer in the hydrogen-rich environment compared with the helium case providing some enlargement of graphene with less hydrogen in its structure. In conclusion, graphene in flakes appears because of the volumetric synthesis in the hydrogen environment. The most promising directions of the practical use of graphеne flakes are apparently related to structural ceramics.
Highlights
According to the Union of Pure and Applied Chemistry (UPAC) definition graphene layer is a single carbon layer of the graphite structure; its nature being an analogy to a polycyclic aromatic hydrocarbon of quasi-infinite size [1]
The presence of hydrogen in the graphene flakes demonstrates its key role in graphene synthesis, which is in agreement with a number of researches [43,44,45]
It is additional found thattreatment. This formation allows direct application ofvarying synthesized without heating of the graphene flakes synthesized in the plasma of any composition output gas always contains hydrogen
Summary
According to the Union of Pure and Applied Chemistry (UPAC) definition graphene layer is a single carbon layer of the graphite structure; its nature being an analogy to a polycyclic aromatic hydrocarbon of quasi-infinite size [1]. 1. Itofisthe a conventional plasma the decomposition of hydrocarbons in the argon or helium plasma jet and subsequent quenching of chemical reactor with water-cooled casing where the end product is manufactured by means of plasma theconsisting resulting of vapor in the formation of the solid deposition on the inner sidesynchronous walls of the jet neutral gasreactor and theand precursor of desired substance. We measured the temperature in the zone of carbon vapor condensation and formation of by means of simplest liquid-packed ring pump controls the arc voltage under the constant current graphene and graphane by the chromel-alumel thermocouple. The current value is chosen on the sharp increase part of the current-voltage characteristics of conditions, the temperature on the collector surface varied within the range of 700–1200 К We obtained the X-ray diffraction spectra from the basic surfaces of the samples
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
