Graphite to Graphene via Graphene Oxide: An Overview on Synthesis, Properties, and Applications

Abstract

This work represents a state-of-the-art technique developed for the preparation of graphene from graphite–metal electrodes by the arc-discharge method carried out in a continuous flow of water. Because of continuous arcing of graphite-metal electrodes, the graphene sheets were observed in water with uniformity and little damage. These nanosheets were subjected to various purification steps such as acid treatment, oxidation, water washing, centrifugation, and drying. The pure graphene sheets were analyzed using Raman spectrophotometry, x-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and tunneling electron microscopy (TEM). Peaks of Raman spectra were recorded at (1300–1400 cm⁻¹) and (1500–1600 cm⁻¹) for weak D-band and strong G-band, respectively. The XRD pattern showed 85.6% crystallinity of pure graphite, whereas pure graphene was 66.4% crystalline. TEM and FE-SEM micrographs revealed that graphene sheets were overlapped to each other and layer-by-layer formation was also observed. Beside this research work, we also reviewed recent developments of graphene and related nanomaterials along with their preparations, properties, functionalizations, and potential applications.

Appendix A

The high-frequency conductivity for Dirac fermions in graphene has been given by the following expression (Eq. A1).

$$ \left( {\frac{{\pi e^{2} }}{2h}} \right) $$

(A1)

For normal incidence light, optical4 transmittance (T) and reflectance (R) are expressed as

$$ T = \left( {1 + \frac{1}{2\pi a}} \right)^{ - 2} \;{\text{and}}\;R = \left( {\frac{1}{{4\pi^{2} a^{2} T}}} \right) $$

(A2)

where α = (2πe ²/hc) ≈ (1/137), e is the electron charge, c is the light speed, and h is Planck’s constant; the opacity is (1 − T) ≈ (πα) ≈ 2.3%.