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 sp 2 - and sp 3 -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 sp 2 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 sp 2 and sp 3 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 sp 2 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 sp 3 type.