First principles calculations of pentaheptite graphene and boronitrene derivatives

We perform first principles density functional calculations to study the stability, structural and electronic properties of pentaheptite graphene and boronitrene derivatives. These systems are comprised of an infinite array of symmetrically paired pentagon and heptagon rings created by applying the Stone Wales transformation over infinite mono-layer graphene and boronitrene. Using the generalized gradient approximation (GGA) and the projector augmented wave (PAW) method, we predict that pentaheptite graphene is metallic and metastable with energy of 0.24 eV/atom above pristine graphene. We deduce that pentaheptite boronitrene is less stable due to the formation of unfavorable B–B and N–N bonds. Our results reveal a significant reduction in the electronic band gap for pentaheptite boronitrene in comparison to pristine boronitrene. Furthermore, we demonstrate that the adsorption of atomic hydrogen on pentaheptite graphene stabilizes the structure and opens a wide band gap of 3.78 eV.