Graphene production by combined bipolar intercalation and high-shear exfoliation

Efficient Graphene Production by Combined Bipolar Electrochemical Intercalation and High-Shear Exfoliation

Abstract

A multitude of bulk graphene production approaches exists, wherein electrochemical exfoliation has shown promising results for large scale production of high quality graphene suspensions. In this study, we demonstrate that bipolar electrochemistry is a viable strategy for ‘wireless’ electrochemical intercalation of graphite flakes as a true bulk process. Expansion of the graphite layers leads to a dramatic 20-fold increase in the yield of subsequent high-shear exfoliation. Large graphite flakes are readily exfoliated in a yield of 16.0 ± 0.2% when exposed to bipolar electrochemical intercalation followed by high-shear exfoliation. Successful graphene production was confirmed by Raman spectroscopy and scanning transmission electron microscopy, showing that the graphene flakes are 0.4–1.5 µm in size with the majority of flakes consisting of 4–6 graphene layers. Moreover, a low intensity of the D-peak relative to the G-peak as expressed by the $I_D / I_G$ ratio in Raman spectroscopy along with high-resolution TEM images reveals that the graphene sheets are essentially undamaged by the electrochemical intercalation. In general, the bipolar electrochemical exfoliation method provides a pathway for intercalation on a wider range of graphite substrates and enhances the efficiency of the exfoliation. The method could be combined with electrochemical functionalization to provide graphene that is specifically designed for a given composite on a larger scale.

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Copenhagen, Denmark
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