▎ 摘　　要

Electron paramagnetic resonance (EPR) spectroscopy was specially employed to investigate the mechanism for graphene fluorination by F-2, which was mainly regarded as molecular addition of F-2 into unsaturated carbons of graphene in previous reports. By observing the changing of spin centers on graphene nanosheet after fluorination, our work demonstrated that graphene fluorination by F-2 was closely involved with radical reactions. The fluorination process comprised by a sequence of radical chain reactions was systematically proposed, and the initiation effect of chemical defects on fluorination reaction of raw graphene was emphasized. In comparison to molecular fluoridation of graphene, the chain radical fluorination can bring about much higher fluorinated degree of fluorinated product. The direct fluorination reactions were also influenced by purity such as oxygen or ferric compound. (c) 2018 Elsevier Ltd. All rights reserved.