Structural and electronic properties of a novel egg-box-like 2D carbon allotrope: A first-principles study

The wide variety of carbon allotropes provides an opportunity to explore novel carbon network-dependent properties and to fabricate future all-carbon nanodevices. This study introduces a novel two-dimensional (2D) carbon allotrope composed of benzene and pentagon rings. Both sp2- and sp3-hybridized carbon atoms exist in this new 2D carbon network, leading to the break of vertical symmetry in the 2D sheet and the exhibition of buckled features with egg-box-like morphology. Based on this allotrope, its hydrogenated and vertical stacking counterparts are further developed as derivative configurations. The structural stability, as well as the associated geometric and electronic properties, has been systematically investigated by first-principles calculations. The results indicate that the new 2D carbon allotrope possesses an inherent metallic behavior with Dirac cones below and above the Fermi level, which can be further tuned to semiconductors with wide bandgaps via either hydrogenation or interlayer covalent bonding. In addition, strain-driven modulations of the structural and electronic properties have also been revealed for the new 2D carbon allotrope and its derivative configurations. Thus, the proposed new 2D carbon allotrope could further expand our understanding of novel low-dimensional carbon allotropes, providing theoretical guidance for future experimental investigations and fabrications of carbon-based nanodevices.