The effect of surfactants and their concentrations on the liquid-exfoliation of graphene

TL;DR

This study examines how different surfactants and their concentrations influence the efficiency of liquid-phase exfoliation of graphene, identifying optimal conditions and mechanisms for stabilization.

Contribution

It provides a comparative analysis of ionic and non-ionic surfactants and their effects on graphene exfoliation, including optimal concentrations and stabilization mechanisms.

Findings

Ionic surfactants increase graphene concentration up to a maximum before plateauing.

Graphene sheets are highly exfoliated and defect-free as confirmed by microscopy and spectroscopy.

Different stabilization mechanisms are explained by colloidal stability theory.

Abstract

We investigated the effect of surfactants and their concentration (Csur) on the final graphene concentration (CG) via the liquid-phase exfoliation method. Six typical surfactants including ionic and non-ionic ones were explored and the optimized Csur for each surfactant was suggested. For ionic surfactants, CG increases with Csur before reaching its maximum and then maintains the high level. The different mechanisms of ionic and non-ionic surfactants in stabilizing graphene dispersions are explained by the theory for colloidal stability. The as-prepared graphene sheets are verified to be highly exfoliated through transmission electron microscopy and atomic force microscopy studies, while the defect-free structure was evidenced by Raman spectra and X-ray photoelectron spectroscopy.