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. 2022 Dec 7;27(24):8643.
doi: 10.3390/molecules27248643.

Electrochemical Exfoliation of Graphite to Graphene-Based Nanomaterials

Michael Salverda  1 , Antony Raj Thiruppathi  1 , Farnood Pakravan  1 , Peter C Wood  2 , Aicheng Chen  1
Affiliations

Electrochemical Exfoliation of Graphite to Graphene-Based Nanomaterials

Michael Salverda et al. Molecules. .

Abstract

Here, we report on a new automated electrochemical process for the production of graphene oxide (GO) from graphite though electrochemical exfoliation. The effects of the electrolyte and applied voltage were investigated and optimized. The morphology, structure and composition of the electrochemically exfoliated GO (EGO) were probed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), FTIR spectroscopy and Raman spectroscopy. Important metrics such as the oxygen content (25.3 at.%), defect density (ID/IG = 0.85) and number of layers of the formed EGO were determined. The EGO was also compared with the GO prepared using the traditional chemical method, demonstrating the effectiveness of the automated electrochemical process. The electrochemical properties of the EGO, CGO and other carbon-based materials were further investigated and compared. The automated electrochemical exfoliation of natural graphite powder demonstrated in the present study does not require any binders; it is facile, cost-effective and easy to scale up for a large-scale production of graphene-based nanomaterials for various applications.

Keywords: electrochemical exfoliation; energy storage; expanded graphite; graphene oxide; graphite.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
Overview of the conversion of natural graphite to electrochemically exfoliated graphene oxide: (i) chemical treatment of graphite to form GIC; (ii) thermal treatment of GIC to form EPG; (iii) electrochemical exfoliation of the EPG foil to produce EGO.
Figure 1
Figure 1
Principle of the automatic ECE system: (A) before ECE; (B) immersion of a fraction of the electrode; (C) the immersed portion was exfoliated; (D) re-immersion of a fraction of the electrode. Current and time plots recorded in 1.0 M NaOH during the ECE process at an applied voltage of: (E) 3.0 V, (F) 4.0 V, and (G) 5.0 V and in 0.5 M NaOH during the ECE process at an applied voltage of: (J) 6.0 V, (I) 8.0 V, and (H) 10.0 V.
Figure 2
Figure 2
(A) Field emission scanning electron microscopy images of GIC before expansion, (B) EPG, (C) EGO, and (D) CGO. Transmission electron microscopic images of (E) EGO and (F) CGO.
Figure 3
Figure 3
(A) Fourier Transform Infrared (FT-IR) spectra of graphite, (B) Raman spectra and (C) X-ray Diffraction (XRD) spectra of graphite, EPG, EGO, and CGO.
Figure 4
Figure 4
(A) Energy dispersive X-ray spectroscopy of EGO and CGO and (B) survey X-ray photoelectron spectroscopy of EGO and CGO and (C) high-resolution X-ray photoelectron spectroscopy (XPS) C1s for EGO and (D) high-resolution C1s for CGO.
Figure 5
Figure 5
(A) Cyclic Voltammogram (CV) performed in 0.5 M H2SO4 at a scan rate 100 mVs−1; (B) CV performed at 50 mV s−1 in 0.1 M KCl + 5 mM potassium ferricyanide.
Figure 6
Figure 6
Scan rate effect studies in 0.5 M H2SO4 of (A) graphite, (B) EPG, (C) EGO, (D) Electrochem-ical reduced EGO (rEGO), (E) CGO, and (F) Electrochemical reduced CGO (rCGO).
Figure 7
Figure 7
(A) Double layer capacitance determination from scan rate studies, (B) A bar chart of dou-ble layer capacitance values of all samples.
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