Continuous Synthesis of Hydrogenated Graphene in Thermal Plasma

© 2018, Pleiades Publishing, Ltd. A single-stage catalyst free synthesis of hydrogenated graphene was studied in the process of methane conversion in a helium plasma jet created by a plasma torch at the power up to 45 kW and the pressure of 710 Torr. The synthesis products were studied by the methods of scanning and transmission electron microscopy, thermal analysis, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analysis

One-step synthesis of N-doped graphene in a plasma jet reactor

© Published under licence by IOP Publishing Ltd. The possibility of doping graphene during its synthesis in a plasma jet of nitrogen has been studied. Direct current plasma torch with power of up to 40 kW was used as plasma jet generator. The source of carbon was propane-butane mixture, acetylene or methane. Synthesized materials are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. It has been shown that XPS spectra of graphene flakes produced in nitrogen plasma differ in atomic nitrogen content. The maximum degree of nitrogen doping of graphene was obtained at decomposition of acetylene at 77 Torr

Distinctive Features of Graphene Synthesized in a Plasma Jet Created by a DC Plasma Torch

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

Continuous Synthesis of Hydrogenated Graphene in Thermal Plasma

© 2018, Pleiades Publishing, Ltd. A single-stage catalyst free synthesis of hydrogenated graphene was studied in the process of methane conversion in a helium plasma jet created by a plasma torch at the power up to 45 kW and the pressure of 710 Torr. The synthesis products were studied by the methods of scanning and transmission electron microscopy, thermal analysis, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analysis

Direct Synthesis of Porous Multilayer Graphene Materials Using Thermal Plasma at Low Pressure

Porous multilayer graphenes have been synthesized by decomposition of hydrocarbons in a thermal plasma jet. Products of synthesis were characterized by electron microscopy, thermogravimetry, Raman spectroscopy, and X-ray diffraction. Possibility of producing a wide range of graphene materials with different morphology and structure has been shown. Influence of the experimental conditions on mesopores structure of the synthesis products has been investigated using the method of “limited evaporation.

One-step synthesis of N-doped graphene in a plasma jet reactor

© Published under licence by IOP Publishing Ltd. The possibility of doping graphene during its synthesis in a plasma jet of nitrogen has been studied. Direct current plasma torch with power of up to 40 kW was used as plasma jet generator. The source of carbon was propane-butane mixture, acetylene or methane. Synthesized materials are characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. It has been shown that XPS spectra of graphene flakes produced in nitrogen plasma differ in atomic nitrogen content. The maximum degree of nitrogen doping of graphene was obtained at decomposition of acetylene at 77 Torr

Graphene Flakes for Electronic Applications: DC Plasma Jet-Assisted Synthesis

The possibility of graphene synthesis (the bottom-up approach) in plasma and the effective control of the morphology and electrical properties of graphene-based layers were demonstrated. Graphene flakes were grown in a plasma jet generated by a direct current plasma torch with helium and argon as the plasma-forming gases. In the case of argon plasma, the synthesized graphene flakes were relatively thick (2–6 nm) and non-conductive. In helium plasma, for the first time, graphene with a predominance of monolayer flakes and high conductivity was grown in a significant amount using an industrial plasma torch. One-dimensional (1D) flow modeling shows that the helium plasma is a less charged environment providing the formation of thinner graphene flakes with low defect density. These flakes might be used for a water-based suspension of the graphene with PEDOT:PSS (poly(3,4-ethylenedioxythiophene): polystyrene sulfonate) composite to create the structures employing the 2D printing technologies. Good structural quality, low layer resistance, and good mechanical strength combined with the ability to obtain a large amount of the graphene powder, and to control the parameters of the synthesized particles make this material promising for various applications and, above all, for sensors and other devices for flexible electronics and the Internet of things ecosystem