Gas-phase Preparation of SO3-Graphite: Host-Exchange and Exfoliation

The reaction of sulfur trioxide with graphite via gas phase led to an intercalation of a double layer of sulfur trioxide with a basal spacing of 11.1 angstrom. The SO3-graphite was obtained atom-efficient as a single phase product without the need of purification. The increased basal space should facilitate an exfoliation by rendering the tactoids more shear labile. A further weakening of the attractive forces within a stack was done by the replacement of sulfur trioxide with the surfactant perfluorobutanesulfonic acid leading to a basal spacing of 16.8 angstrom. The large basal spacings were also preserved in suspension and no defects were created. The mechanical exfoliation with ultrasound predominantly broke the platelets. A rotor-stator device offering high shear forces was found to exfoliate the platelets more gently but there was still a good number of very small particles.