Electrochemical synthesis and physical–chemical characterization of the low-oxidized graphite fluoroxide materials

A process of anodic oxidation of purified natural graphite in aqueous 11–45% HF solutions has been studied at constant voltages 5–7 V. New types of low-oxidized graphite fluoroxide materials (FOG-E) were isolated, prepared under electrochemical synthesis conditions only. Electrochemical oxidation of graphite should include in a first step the reaction of evolving oxygen and O-containing groups with surface carbon atoms on graphite particles and a subsequent formation of C–OH bonds, and in a second step, a partial substitution of the latter groups into C–F groups. Chemical and physical–chemical study of FOG-E showed that they are multiphasic materials. The low-oxidized graphite fluoroxide materials are excellent precursors for the preparation of thermally expanded graphite (TEG).