Vaiva Nagyte: Raman Spectroscopy of Electrochemically Exfoliated Graphene

Vaiva Nagyte*, Daniel J. Kellyº, Gennaro Picardi*, Alexandre Felten⁰, YuYoung Shin*, Adriana Alieva *, Robyn E. Worsley*, Khaled Parvez*, Andrew Pollard†, Cinzia Casiraghi*  *School of Chemistry, ºSchool of Materials, and ‡National Graphene Institute, University of Manchester, Manchester, M13 9PL, United Kingdom,  National Physical Laboratory, Teddington, Middlesex, TW11 0LW, United Kingdom, ⁰Synthesis, Irradiation and Analysis of Materials (SIAM), University of Namur, rue de Bruxelles 61, Namur, 5000, Belgium  One of the most promising mass scalable techniques for production of graphene is given by the electrochemical exfoliation (ECE) of graphite [1]. The accurate characterization of such graphene dispersions is crucial in order to assess the properties of the material produced  (flake size and thickness distribution, type and amount of defects, etc.) and develop metrology standards for the commercialization of solution-processed graphene. Nevertheless, the Raman characterization of electrochemically exfoliated graphene has been rather limited: transmission electron microscopy (TEM) and atomic force microscopy (AFM) are typically used to analyse the graphene flake’s morphology, while the physical properties and chemical composition are typically evaluated by X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD) [2,3]. Furthermore, AFM is not a reliable technique for thickness evaluation, and XPS and XRD are bulk characterization techniques, while Raman spectroscopy probes individual ECE graphene sheets. In addition to this, most of the works on graphene produced by ECE only report a few Raman spectra, and they may not be representative of the different type of graphene flakes in the dispersion.  In this work we show a systematic Raman spectroscopy analysis of graphene produced by ECE, using different electrolytes and solvents. We evaluate electrochemical exfoliation efficiency by Raman spectroscopy and investigate the process parameters that influence the quality of the graphene dispersions.  [1] Parvez, K. et al. Synth. Met. 2015, 210, 123–132. [2] Lv, W. et al. ACS Nano. 2009, 3 (11), 3730–3736. [3] Coroş, M. et al. RSC Adv. 2016, 6 (4), 2651–2661. Vaiva Nagyte is currently a Ph.D. in Cinzia Casiraghi’s group at the University of Manchester working under supervision of Sarah Haigh, Antonios Oikonomou, Andrew Pollard, and Cinzia Casiraghi. Her research interests are Raman spectroscopy, 2D materials exfoliation and standardisation in partnership with National Physical Laboratory. She received her joint M.Sc. in Nanoscience and Nanotechnology from KU Leuven and Chalmers University of Technology and B.Sc. in Applied Physics from Vilnius University.