Role of electrolyte at the interface and in the dispersion of graphene in organic solvents

The electrochemical exfoliation of graphene is a very useful technique to prepare highly conductive graphene with a low defect level. However, low dispersion stability is a barrier to this process being used to prepare graphene directly in a wide range of applications. Even though the dispersion stability and concentration of graphene are important, the reasons for the lower dispersion stability and lower concentration of electrochemically exfoliated graphene have not yet been clarified. In this study, we identified that the strong electrostatic attractive interaction between charged ions from electrolytes at the interfaces of graphene layers substantially deteriorated the dispersion stability. Both the stability and the concentration of graphene dispersions were substantially enhanced upon removal of the residual electrolytes from the organic solvents used in this study.