Towards large-scale in free-standing graphene and N-graphene sheets

Abstract

One of the greatest challenges in the commercialization of graphene and derivatives is production of high quality material in bulk quantities at low price and in a reproducible manner. The very limited control, or even lack of, over the synthesis process is one of the main problems of conventional approaches. Herein, we present a microwave plasma-enabled scalable route for continuous, large-scale fabrication of free-standing graphene and nitrogen doped graphene sheets. The method’s crucial advantage relies on harnessing unique plasma mechanisms to control the material and energy fluxes of the main building units at the atomic scale. By tailoring the high energy density plasma environment and complementarily applying in situ IR and soft UV radiation, a controllable selective synthesis of high quality graphene sheets at 2 mg/min yield with prescribed structural qualities was achieved. Raman spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and Near Edge X-ray-absorption fine-structure spectroscopy were used to probe the morphological, chemical and microstructural features of the produced material. The method described here is scalable and show a potential for controllable, large-scale fabrication of other graphene derivatives and promotes microwave plasmas as a competitive, green, and cost-effective alternative to presently used chemical methods.

Large-scale synthesis of free-standing N-doped graphene using microwave plasma

“…In the present work, in-situ direct synthesis of free-standing N-graphene flakes at a relatively high yield (~ 1.3 mg min −1 ), was achieved in a single step by employing microwave plasma (see supplementary material) operating at atmospheric pressure conditions 40 – 44 . An ethanolic solution of ammonia (4 wt %) was used as precursor of both carbon and nitrogen.…”

“…The plasma properties have been tailored to achieve selective synthesis of free-standing N-graphene sheets. The flowing sheets were submitted to UV and IR irradiation in the post-plasma zone during their flight to the collecting system to further improve their structural quality 40 . Raman spectroscopy, SEM and TEM and XPS were used to characterize the morphology, microstructure and chemical properties of the synthesized material.…”

Synthesis of a zinc oxide/graphene hybrid material by the direct thermal decomposition of oxalate

“…In the spectra of the remaining three samples, the red peak at about 284.8 eV is attributed to graphitic sp 2 carbon [19,20,47,49]. The peaks around 285.4 and 287.1 eV are attributed to C-O and C=O respectively, and the very broad peak around 290 eV is the result of the sp 2 carbon π→π * 'shake-up' satellite [50].…”

Graphene synthesized in atmospheric plasmas—A review

“…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.…”

“…The morphology of crumpled graphene has been compared with that of crumpled paper. 43,52 However, GSG may be crumpled because of the presence of graphitic nanocrystals in the synthesized sheets. 71 In situ TEM has revealed that graphitic nanocrystals provide GSG with additional mechanical stability, enable the material to reversibly deform, and prevent GSG from being flattened like paper.…”