Solution plasma exfoliation of graphene flakes from graphite electrodes

Abstract

Graphene flakes were successfully produced by a simple method named a solution plasma process. The plasma was generated between two carbon electrode tips which were immersed in distilled water. The production approach is a continuous energy accumulation induced by focusing of plasma streamers on the surface of electrodes. This focused energy produces thermal gradient zones where a proper energy level is produced. Concisely, the energy is enough to extract graphene layers from the graphite structure but not enough to break covalent C–C bonds within the graphene sheets. Optical emission spectroscopy results showed the decomposition of carbon from the graphite electrodes with different intensities for the carbon species. Transmission electron microscopy images confirmed the hexagonal honeycomb structure of the graphene flakes. Furthermore, broadening of the 2D band in the Raman spectra revealed that the graphene flakes were disordered multilayers.