From Zigzag Nanoribbons to Dirac Materials: A Carbon Ring-Bridge Design Strategy

Based on first-principles calculations, we propose a series of new two-dimensional (2D) carbon allotropes exhibiting Dirac cone features. The allotropes are composed of zigzag graphene nanoribbon, pentagon, and square carbon rings and can be denoted as (ZPS) _<i>n</i> -graphene. The stability and electronic properties of (ZPS) _<i>n</i> -graphene are systematically investigated. The results confirm that (ZPS) _<i>n</i> -graphene is energetically, dynamically, and thermodynamically stable. (ZPS) _<i>n</i> -graphene possesses semimetallic character, with a Dirac cone locating along the high-symmetry path. Owing to the particular framework, the Dirac cone is distorted and exhibits anisotropic transport properties. The Fermi velocity of (ZPS)₂-graphene can reach up to 1 × 10⁶ m/s along the <i>k</i> _<i>x</i> direction. Strain engineering reveals that the Dirac cone in (ZPS)₂-graphene remains largely unaffected by uniaxial strain along the <i>x</i> or <i>y</i> direction. The ring-bridge design strategy provides a promising route for engineering emergent electronic properties, and these findings will expand the members of 2D carbon allotropes with the Dirac cone and widen the application of graphene nanoribbon.