Simple preparation and application of high quality graphene flakes without oxidation by using potassium salts

Abstract

Preparation of graphene flakes without oxidation is important to preserve the superb intrinsic properties of graphene. Here we propose a new and simple route to produce few layer, flake type graphene with minimized oxidation (< 2 %) by the intercalation of potassium to raw graphite using potassium salts. A chemical reaction between potassium iodide (KI) and 1,2-dichlorobenzene (1,2-DCB) in an autoclave at approximately 300 ℃ supplies free potassium that can spontaneously intercalate into the graphite, as verified by gas chromatography. This process produces high quality graphene flakes using inexpensive and easily handed metal salts. As a reference of high quality graphene, the average value of the intensity ratio of D peak to G peak from a Raman spectroscopy analysis is 0.549. The conductivity of the prepared graphene is measured to be 11,033 S m^${-1}$. These values demonstrate that the graphene produced here is superior to that obtained by Hummers’ method of preparing reduced graphene from oxidized graphite.