Shear Assisted Electrochemical Exfoliation of Graphite to Graphene

Abstract

The exfoliation characteristics of graphite as a function of applied anodic potential (1-10 V) in combination with shear field (400-74 400 s(-1)) have been studied in a custom-designed microfluidic reactor. Systematic investigation by atomic force microscopy (AFM) indicates that at higher potentials thicker and more fragmented graphene sheets are obtained, while at potentials as low as 1 V, pronounced exfoliation is triggered by the influence of shear. The shear-assisted electrochemical exfoliation process yields large (∼10 μm) graphene flakes with a high proportion of single, bilayer, and trilayer graphene and small ID/IG ratio (0.21-0.32) with only a small contribution from carbon-oxygen species as demonstrated by X-ray photoelectron spectroscopy measurements. This method comprises intercalation of sulfate ions followed by exfoliation using shear induced by a flowing electrolyte. Our findings on the crucial role of hydrodynamics in accentuating the exfoliation efficiency suggest a safer, greener, and more automated method for production of high quality graphene from graphite.

Numerical study of the electrochemical exfoliation of graphite

“…The stresses gradient along graphite rod is in the range (3.43 × 10 −8 -5.77 × 10 −7 ) N/m 2 which is appropriate stress to breakdown the weak van der Waals band between graphene sheets to exfoliate graphite. In previous work which done by Shinde et al used COMSOL Multiphysics to simulate exfoliation of graphite and they showed that the shear rate played a main role in the exfoliation process [35]. In this study, we presented the full description of the electrochemical exfoliation of graphite numerically and the role of electrolyte in this process.…”

“…However, few papers were published depicting the exfoliation mechanism of graphite. Shinde et al [35] studied electrochemical exfoliation of graphite by shear assisting to exfoliate graphene and simulated this process using COMSOL Multiphysics. They stated that the shear rate played a main role on the yield, thickness and quality of exfoliated graphene.…”

Towards scale‐up of graphene production via nonoxidizing liquid exfoliation methods

“…The slow kinetics in cathodic exfoliation limits its scalability in industry. Shinde et al proposed a combination of two mechanisms to efficiently exfoliate graphite . Applying minimal anodic potential, the oxidative effect was reduced.…”

Green Intelligent Nanomaterials by Design (Using Nanoparticulate/2D-Materials Building Blocks) Current Developments and Future Trends

“…Studying the influence of varying parameters like anodic bias (1-10 V), and shear field (400-74,400/s) concluded that thicker and more fragmented graphene sheets were formed at higher biases, while at potentials as low as 1 V, shear force could cause pronounced exfoliation. This process under optimum condition could produce large graphene flakes (∼10 μm) with a high proportion of single, bilayer, and trilayer graphene and small I D /I G ratio (0.21-0.32) with only a small contribution from carbon-oxygen species [312]. Biomolecules are also attracting attentions as dispersants for 2D materials providing a number of advantages over more conventional, synthetic surfactants particularly in case of biomolecules including proteins and peptides, nucleotides and nucleic acids (RNA, DNA), polysaccharides, plant extracts and bile salts as colloidal dispersants as discussed in a recent review [313].…”