Realizing Graphene-like Dirac Cones in Triangular Boron Sheets by Chemical Functionalization

The most important feature in graphene is its unique Dirac cone, which is closely associated with many novel properties. However, this type of Dirac cone is rare and difficult to realize in non-group-IV two-dimensional (2D) materials. In this work, we have theoretically designed a family of triangular B3X (X = H, F, and Cl) monolayers with graphene-like Dirac cones in terms of constituent atomic orbitals and high thermal stability. Furthermore, based on the idea of effective charge transfer, we have uncovered the key mechanism for the realization of graphene-like Dirac cones with a concise bond distribution model, which is valid for the 2D boron-based materials with a single Dirac cone and double Dirac cones. Our results offer new insights into the design of 2D boron-based Dirac semimetals by chemical adsorption, which may stimulate the development of 2D boron research.