Tile-like carbons: Two novel 2D allotropes with sp 2+ sp 3 hybridized network

Research on two-dimensional carbon materials with unique structures and special electronic and mechanical properties has always been one of the main goals of engineers to discover and develop carbon-based allotropes. In the present work, the structural, thermal, mechanical and electrical properties of the two novel 2D carbon allotropes alpha-TileC26 and (3-TileC32 with mixed sp2 + sp3 hybridized network on the basis of density functional theory were investigated. Tile-like carbons have tetragonal symmetry and belong to the P4mm (No. 99) space group. The alpha-TileC26 sheet has a periodic arrangement of four-and five-membered rings and molecules with four pentagons, while the (3-TileC32 sheet has a periodic arrangement of four-, five- and six-membered rings and including molecules with two pentagons and two hexagons, respectively. First-principles calculations and molecular dynamics simulations confirmed their dynamical, mechanical, structural and thermal stabilities. Our calculations from electronic band structure of alpha-TileC26 carbon reveal that this structure has a metallic behavior, whereas band structure of (3-TileC32 carbon indicates that this structure is a direct semiconductor and its band gap is about 1.18 eV at Y point. Such studies can provide a suitable approach to predict and experimental synthesis 2D carbon allotropes composed of polygons with their excellent properties. The obtained results show that new carbon-based two-dimensional sheets can be potential candidates for applications in nano-electronic devices.