Emil Tveden Bjerglund: Efficient graphene production by combined bipolar electrochemical intercalation and high-shear exfoliation

posted 2 Jun 2017, 02:10 by Peter Boggild   [ updated 2 Jun 2017, 04:43 ]
Emil Tveden Bjerglund†, Michael Ellevang Pagh Kristensen†∥, Samantha Stambula‡, Gianluigi A. Botton‡§#, Steen Uttrup Pedersen†*, and Kim Daasbjerg†*

† Carbon Dioxide Activation Center. Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark 
‡ Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, L8S 4L8, Canada
§ Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada L9S 4M1
# Canadian Centre for Electron Microscopy, McMaster University, Hamilton, Ontario, Canada L8S 4M1
∥ Radisurf Aps, Arresøvej 5B, 8240 Risskov, Denmark

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 17.6 ± 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 ID/IG 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.

Emil Tveden Bjerglund is currently a Ph.d.-student in the Organic Surface Chemistry group under the supervision of Kim Daasbjerg and Steen Uttrup Pedersen. He recieved his B.Sc. degree in nanoscience in 2013 and his M.Sc. in nanoscience in 2016, both from Aarhus University. His interests are electrochemical production and functionalisation of graphene materials for polymer composites.