Scalable graphene production from ethanol decomposition by microwave argon plasma torch

Abstract

A fast, efficient and simple method is presented for the production of high quality graphene on a large scale by using an atmospheric pressure plasma-based technique. This technique allows to obtain high quality graphene in powder in just one step, without the use of neither metal catalysts and nor specific substrate during the process. Moreover, the cost for graphene production is significantly reduced since the ethanol used as carbon source can be obtained from the fermentation of agricultural industries. The process provides an additional benefit contributing to the revalorization of waste in the production of a high-value added product like graphene. Thus, this work demonstrates the features of plasma technology as a low cost, efficient, clean and environmentally friendly route for production of high-quality graphene.

Graphene synthesized in atmospheric plasmas—A review

“…Precursors enter the region of the plasma where microwave power is absorbed by the plasma electrons (this region is hereafter referred to as the coupler region). Plasma electrons transfer energy to heavy particles (ions and neutral atoms) through elastic and inelastic collisions in the coupler region, which is an environment that has an electron density $10 13 cm À3 and gas temperatures as high as 3000 K. [27][28][29] Precursors that enter the coupler region are decomposed into smaller reactive fragments, such as C, H, H 2 , C 2 , C 2 H 2 , and CO. [27][28][29][30][31] These reactive fragments then flow out of the coupler region and into the plasma afterglow, where they react to form nuclei that rapidly grow into GSG. 26,29 The entire process of precursor delivery, decomposition, and GSG formation takes place over a time period on the order of 10 À1 s. 25,28 GSG sheets exit the plasma afterglow and are typically collected downstream from the plasma on filters.…”

“…25 Since this discovery, plasma reactors with different designs have been utilized to create GSG. [27][28][29][30][31]35,[41][42][43] For example, GSG can be produced through the delivery of ethanol into surface wave-induced microwave plasmas at atmospheric conditions 28,29,31 [44][45][46][47] can also generate atmospheric pressure Ar plasmas that are capable of creating GSG. 27 A TIAGO consists of a waveguide whose central section is reduced in height [ Fig.…”

“…However, lower reactor pressures are not favorable to the formation of GSG. 27 This is because atmospheric plasmas are collisional environments that can achieve the high gas temperatures (3000 K) required for the formation of carbon nanostructures. Collisions between electrons and heavy particles are reduced in subatmospheric microwave plasmas, which results in decreased temperatures that prevent the formation of GSG.…”

“…Collisions between electrons and heavy particles are reduced in subatmospheric microwave plasmas, which results in decreased temperatures that prevent the formation of GSG. 27 On the other hand, a higher reactor pressure (1.5 atm) has been shown to increase production rates of GSG. 35 Despite the increase in GSG formation at higher pressure, future research should concentrate on optimizing the synthesis of GSG in atmospheric pressure environments because production at ambient conditions will greatly facilitate the large-scale production of the material.…”

“…6(b)] are collected from reactor walls, which are in close proximity to the Ar plasma. 27 The role of the coupler region in atmospheric plasma reactors could be similar from system to system. However, the variation in MFP conditions and the difference in materials deposited on the walls of various reactors suggest that the mechanisms of GSG formation are dependent on reactor design.…”