Structure and electronic properties of graphyne layers modeled on layers of graphene L3–12

Abstract

In the present paper, a theoretical study of the structure and electronic properties of new polymorphic conformations of graphyne layers modeled on layers of graphene L 3-12 was performed. Graphyne layers have been constructed by replacing carbon-carbon bonds between three-coordinated (sp 2-hybridized) atoms in the graphene layer of L 3-12 with diatomic carbyne chains. Geometric optimization and examination of electronic properties of novel graphyne architectures were performed within the framework of density functional theory using the gradient approximation. Calculations have shown the possibility of stable existence of three main polymorphic conformations of graphyne layers. The graphyne layers were designed by incorporating a carbyne chain into the initial L 3-12-graphene layer by following rules: for the γ-L 3-12-graphyne layer, one bond of each three-coordinated atom was substituted by a carbyne chain, for the β-L 3-12-graphyne layer, two bonds of those atoms were replaced, and for α-L 3-12-graphyne layers three bonds were replaced. The sublimation energy of the graphyne layers is in the range from 6.52 to 6.61 eV / atom that is less than the sublimation energy of the original L 3-12 graphene layer (6.66 eV / atom) as well as the sublimation energy of hexagonal graphene (7.76 eV / atom). However, the value of the sublimation energy of the graphyne layers is in the range of experimentally synthesized carbon materials that are stable under normal conditions. All the graphyne layers studied in this work are semiconductors with the energy gaps widths from 0.18 to 0.91 eV.

Effect of external pressure on the hydrogen storage capacity of a graphene flake: molecular dynamics

“…% [10]. Therefore, many theoretical and experimental works have been carried out to find ways to increase the sorption capacity of carbon structures [11][12][13][14][15][16][17][18][19][20]. These works have demonstrated that reduction of the temperature and increasing of pressure have a very positive effect on the hydrogen storage by carbon structures.…”

Effect of deformation on dehydrogenation mechanisms of crumpled graphene: molecular dynamics simulation

“…The search of new carbon structures has not ceased over the past decades due to its unique properties found both in theoretical and experimental studies [1][2][3][4][5][6][7][8][9][10][11][12][13]. To date, carbon aerogels [1], crumpled graphene [2 -4], pillared graphene [5,6], moiré graphene bilayers [7], diamondlike carbon phases [9 -13] and many others have been experimentally synthesized or theoretically studied.…”