Increasing the production of high-quality graphene nanosheet powder: The impact of electromagnetic shielding of the reaction chamber on the TIAGO torch plasma approach

Abstract

Microwave-induced plasmas (MIPs), and specifically the TIAGO device (Torche à Injection Axiale sur Guide d’Ondes), offer a streamlined, cost-effective, and environmentally friendly technique for producing high-quality graphene powder in a reaction chamber by a single-step process through ethanol decomposition. To optimize graphene synthesis process, a pivotal move involves minimizing energy dissipation through radiation to maximize the available microwave energy input. Including a metallic shielding around the reaction chamber, essentially creating a Faraday cage, is proposed. The shielding strategy prevents radiation losses and results in a remarkable increase in solid material formation up to 22.8 %. This value, along with the emitted gases proportions and plasma volume increase, shows a correlation with conditions associated with higher input power. Crucially, the shielding of the reaction chamber does not modify graphene growth kinetics in the plasma, as confirmed by Optical Emission Spectroscopy. The synthesized material undergoes a thorough examination, employing diverse techniques like Raman spectroscopy, electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and Brunauer-Emmett-Teller (BET) analysis. These analyses underscore a consistent quality of graphene, unaffected by the shielding implementation. Therefore, electromagnetic shielding of the TIAGO torch discharge not only leads to a remarkable increase in solid material formation, thus energy yield, but does so without compromising the intrinsic properties and quality of the synthesized graphene.