A DFT study on graphyne fluorination

Resumo

Graphynes, lattices of benzene rings connected by acetylene bonds, are mono-atomic-thick planar sheets of sp- and sp²-bonded carbons (C_I and C_II, respectively), differing from sp² 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 F₂ 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 + 9F₂ → Graphyne-F₁₈.