Modern Methods for Synthesis of Few-Layer Graphene Structures by Electrochemical Exfoliation of Graphite

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Abstract—A review of methods for synthezing few-layer graphene structures (FGS) by electrochemical exfoliation of graphite in aqueous solutions of inorganic substances and ionic liquids is conducted. The expected mechanisms of the processes are considered, as well as the influence of the electrolysis regimes on the quality characteristics of the product obtained. In general, the method of electrochemical exfoliation of graphite is based on the destruction of graphite-containing materials in solutions of certain substances containing ions that can undergo intercalation into graphite under the action of electric current. The procedure of electrochemical exfoliation of graphite contains two stages, the first of which corresponds to the intercalation of ions from the electrolyte solution into the space between the graphene sheets to form covalent or ionic bonds, and the second involves the separation of the material as a result of the electrochemical reaction. At first, a potential, as a rule, smaller compared to the operating one, is applied to the electrode to be destroyed in order to achieve good surface wetting and preliminary intercalation of graphite. At the next step, the main stage of obtaining the FGS begins, which is characterized by imposing an operating voltage. Then, as a rule, surfactants are added to the solution, facilitating exfoliation, as well as reducing the agglomeration of the obtained FGS suspensions. The stages of separation and purification of the obtained product are described.