Graphene has attracted tremendous interest due to its extraordinary electrical, thermal, and physical properties. The graphynes are widely investigated for their variety of structures and electrical properties. Using the ab initio global search approach, we predicted three hexagonal and one tetragonal two-dimensional carbon allotrope: C65-, C63-, C31- and C41-sheets. Graphene, C65-sheet, graphenylene, C63-sheet, and graphyne form a series of graphene-like allotropes from graphene to graphyne. These four new carbon allotropes are metallic and are local minimums in their potential energy surfaces. These two-dimensional carbon allotropes are expected to serve as precursors to build various nanotubes, fullerenes, nanoribbons, and other low-dimensional nanomaterials.
