Microscopic nature of mobile fluoride anions on sp2 carbon surfaces

Abstract

We use ab initio theories to investigate the configuration of the mobile fluoride acceptor anions on sp(2)-bonded carbon materials. We find that trifluoride anion (F-3(-1)) is bound onto the graphene plane through ionic interaction, shifting the Fermi level rigidly without perturbing the pi electron structures. This suggests that the F-3(-1) can easily migrate, generating hole carriers in graphitic materials. On the other hand, the monatomic fluoride anion is not stable against the formation of the C-F bond, and F-2 molecule does not adsorb. We suggest that the widely debated semi-ionic C-F bond is not a relevant model for fluorinated graphites.