A DFT study on graphyne fluorination

Graphynes, lattices of benzene rings connected by acetylene bonds, are mono-atomic-thick planar sheets of sp - and sp 2 -bonded carbons (C I and C II , respectively), differing from sp 2 hybridized graphenes. Here, employing density functional calculations, we investigated the f luorination of a graphyne layer with atomic and molecular f luorines. It was found that atomic F prefers to be adsorbed on a C II atom, releasing an energy of 2.25 eV. The molecular F 2 was found to be adsorbed on a −C≡C− linkage and dissociated to two F atoms. In the most stable state, calculated barrier and dissociation energies for this process are about 2.90 and 4.02 eV. Both atomic and molecular interaction processes significantly reduce the HOMO/LUMO gap. Finally, we investigated the thermodynamic feasibility of the following reaction: Graphyne + 9F 2 → Graphyne-F 18 .