High-yield graphene production by electrochemical exfoliation of graphite: Novel ionic liquid (IL)–acetonitrile electrolyte with low IL content

Electrochemical exfoliation of graphite assisted by ionic liquids (ILs) has been proposed as a high-throughput, green and scalable graphene production technique. Previous research has focused on IL/water electrolytes with high IL content (from 1:0.1 to 1:1IL/water volume ratios). Here, we introduce and investigate a novel IL/acetonitrile electrolyte with dramatically lower loads of ionic liquids (∼1:50IL/acetonitrile vol. ratio). Our approach provides three main advantages: cost efficiency due to low IL content, extended electrochemical stability in a non-aqueous electrolyte, and high exfoliation yield by effective anionic intercalation within the graphitic layers. Using iso-molded graphite rod as the anode, we achieved up to 86% of exfoliation with the majority of the products as graphene flakes in addition to smaller quantities of carbonaceous particles and rolled sheets. We also demonstrate by Raman spectroscopy the beneficial sonication effect on improving the quality of the graphene-based products. Moreover, in contrast with previous literature, we prove that the electrolyte coloration during electro-exfoliation in the IL media is related to the occurrence of diverse reactions involving the IL moieties and cannot be associated with different stages of graphene formation. The cathodically generated species can also interfere with the anionic intercalation in the graphite anode.