A green approach to the synthesis of high-quality graphene oxide flakes via electrochemical exfoliation of pencil core

Abstract

A simple, green and cost-effective approach has been reported to synthesize high-quality graphene oxide (GO) flakes via electrochemical exfoliation of pencil cores in aqueous electrolytes. The exfoliated GO flakes exhibit excellent electrocatalytic activity and toxicity tolerance for oxygen reduction reactions in alkaline solution. Our present results are promising for scaled-up preparation and further commercialization of graphene oxide in a low-cost and environmentally friendly way.

High quality, low oxygen content and biocompatible graphene nanosheets obtained by anodic exfoliation of different graphite types

“…Although a variety of electrochemical processes have been successfully tested towards this end [19], they can be broadly classified into either (1) cathodic exfoliation in organic solvents (propylene carbonate, dimethyl sulfoxide, etc) containing lithium or alkylammonium salts as the electrolyte [20][21][22][23][24], or in water in some specific cases [25] or (2) anodic exfoliation in ionic liquid-water mixtures or aqueous solutions of acids (mainly H 2 SO 4 ) or inorganic salts [26][27][28][29][30][31][32][33]. The anodic exfoliation protocols are particularly attractive due to their greener character (use of water/ionic liquids vs. organic solvents) and generally higher and faster production rates.…”

Synthesis of Graphene Nanosheets through Spontaneous Sodiation Process

“…A relatively lower amount of graphene is produced when exfoliation occurs via ionic liquids, the lateral size of the product is small, and the electronic properties of graphene are distorted due to functionalization with ionic liquids [16,20]. While acidic electrolytes for exfoliation lead to graphene having a higher quality and a greater lateral size, however, over-oxidation of graphite by acid occurs, leading to the presence of oxygen-containing functional groups [17,18,21].…”

An Oxygen Reduction Study of Graphene-Based Nanomaterials of Different Origin

“…Moreover, the value of n is between two and three in case of GC/Graphene1 and GC/rGO, but even higher in case of GC/Graphene2 and GC/GO at higher potentials (see Figure 9 and Figure S5). Higher electron transfer number at high overpotentials on graphene-based electrodes has been also reported in the literature [35,[73][74][75]. It is well-known that the graphene nanosheets are prone to agglomerate due to the van der Waals interaction yielding a multilayer graphene structure, which in turn leads to the loss of the electrocatalytic activity for ORR.…”