Structural Investigation of the Synthesized Few-Layer Graphene from Coal under Microwave

Abstract

This study focused on the structural investigation of few-layer graphene (FLG) synthesis from bituminous coal through a catalytic process under microwave heat treatment (MW). The produced FLG has been examined by Raman spectroscopy, XRD, TEM, and AFM. Coal was activated using the potassium hydroxide activation process. The FLG synthesis processing duration was much faster requiring only 20 min under the microwave radiation. To analyse few-layer graphene samples, we considered the three bands, i.e., D, G, and 2D, of Raman spectra. At 1300 °C, the P10% Fe sample resulted in fewer defects than the other catalyst percentages sample. The catalyst percentages affected the structural change of the FLG composite materials. In addition, the Raman mapping showed that the catalyst loaded sample was homogeneously distributed and indicated a few-layer graphene sheet. In addition, the AFM technique measured the FLG thickness around 4.5 nm. Furthermore, the HRTEM images of the P10% Fe sample contained a unique morphology with 2–7 graphitic layers of graphene thin sheets. This research reported the structural revolution with latent feasibility of FLG synthesis from bituminous coal in a wide range.

Graphene growth via chemical vapour deposition on cross-rolled surface-textured nickel–copper foils

“…Raman spectroscopy stands out as the simplest and most widely used technique for determining the number of graphene layers. The estimation of the layer count can be achieved through three different methods: (i) analysing the intensity of the G band 26,61 and the intensity ratio of the 2D and G bands, 62,63 (ii) examining the frequency of the shear vibration mode, 64,65 and (iii) conducting shape analysis of the 2D band. 62,66,67 Das et al 62 determined the number of graphene layers using the I G /I 2D intensity ratio.…”

Carbon Transformation Induced by High Energy Excimer Treatment

“…The chemical and surface changes induced by excimer laser wavelength were also observed for silicon and semiconductors [52,53] or silicon carbide [54][55][56]. The discussion on the correlation of surface morphology (e.g., SEM and AFM images) and I D /I G ratio changes were included in the papers [57,58].…”

Preparation of Coal-Based Graphene by Flash Joule Heating

“…Consequently, a need persists for a rapid, simple, cost-effective, and scalable production process. 18 Flash Joule heating (FJH) was first introduced by Luong et al in a 2020 Nature publication. This process converts carboncontaining feedstocks, including carbon black, waste plastics, rubber tires, coal, and coal pitch, into high-quality turbo graphene (tFG).…”

“…These techniques each exhibit drawbacks, limiting their scalability for graphene production. Consequently, a need persists for a rapid, simple, cost-effective, and scalable production process …”

“…Consequently, a need persists for a rapid, simple, cost-effective, and scalable production process. 18 …”