Contribution of Different Exfoliation Mechanisms in the Bipolar Electrochemical Fabrication of Graphene

Abstract

Since the discovery of graphene, two-dimensional (2D) materials have attracted increasing interest due to their extraordinary properties such as high thermal conductivity, high specific surface area, and broad electrochemical window. In general, different techniques have been employed to fabricate these materials, including chemical vapor deposition, mechanical, chemical, and electrochemical exfoliation. Bipolar electrochemistry (BPE) is one of the newest methods which has been used for the fabrication of 2D materials. In our previous study, a modified BPE concept was developed for simultaneous exfoliating and deposition of both reduced graphene oxide (rGO) and graphene oxide (GO) layers on conductive objects. Although the characteristics of the produced materials have been studied and reported, there are still remaining questions that need more investigations to be answered. The main focus of this study is investigating the active exfoliation mechanisms in the BPE process and finding out the dominant exfoliation reactions (either cathodic or anodic exfoliation).For this purpose, a novel and unique modified bipolar system has been developed, which could retard either anodic or cathodic exfoliation of graphite by replacing the relevant sites of the bipolar electrode with a platinum wire. This helped to have a better understanding of the source of produced rGO and GO. The morphology and functional groups of deposited materials on both negative and positive feeding electrodes were investigated when the graphite was polarized to either positive or negative potentials. The results proved that both anodic and cathodic exfoliation mechanisms are active at the same time when using graphite as the bipolar electrode. However, the morphology, functional groups, level of oxidation, the bipolar current, and deposition rate vary according to the exfoliation mechanism. The developed modified BPE technique and materials characterizations will be discussed in detail at the conference.Keywords: Electrochemical exfoliation, bipolar electrochemistry, 2D materials, graphene fabrication