Anion intercalated graphite: a combined electrochemical and tribological investigation by in situ AFM

The intercalation of graphite by electrochemical methods is an efficient strategy to produce massive graphene flakes. In fact, when graphite is biased inside an acidic solution, an ions enter inside the stratified structure of the electrode and reduce the layer-to-layer interaction. Consequently, a gentle sonication is sufficient to disperse the graphene flakes inside the electrolyte. In view of an optimisation of the production protocol,adetailedanalysisof theintercalationmechanismat the molecular length scale is mandatory. In the last 30 years, electrochemical (EC) scanning probe microscopies (e.g. EC STM and in situ AFM) have been widely exploited in this re search topic. In fact, these techniques have the possibility of combining the EC characterisation (e.g. cyclic-voltammetry, CV)withmechanicalcharacterisation (e.g. adhesion and fric tion)andtopographyacquisitionwithhigh(molecular)lateral resolution. In this work, we investigate the tribological properties of the basal surface of graphite before and after the anion interca lation. By comparing the results acquired after the extraction of the graphite electrode from the EC cell with those collected inside the EC cell during the CV by an in situ AFM, we show how some features deriving from anisotropic friction can be exploited to unveil the very early stage of graphite exfoliation.