Synthesis and Characterization of Highly Fluorinated Graphite Containing sp2 and sp3 Carbon

Highly fluorinated graphites were obtained by reaction of fluorine with graphite, at room temperature, in the presence of iodine pentafluoride and hydrogen fluoride. The re-fluorination between 100 and 600 °C yielded a series of fluorinated graphites with semi-ionic and covalent C−F bonds with varying amounts of sp2- and sp3-type carbon hybridization. Three types of materials have been generated: for re-fluorination lower than 400 °C, the C−F bond is still mainly semi-ionic and the carbon atoms are sp2 coplanar; for re-fluorination temperatures between 400 and 550 °C, "hybrid" graphite fluorides characterized by two types of C−F bonds, semi-ionic and covalent, with sp2 and sp3 carbon hybridization were found. For higher re-fluorination temperatures (between 550 and 600 °C), despite a similar fluorination amount and a covalent C−F bond, the sp2 character never completely vanished even at a high re-fluorination temperature of 600 °C. At such a temperature, a directly fluorinated graphite would be of the pure sp3 type.