Epitaxial Growth of Molecular Graphene on Metal Surface Alloy

Abstract Molecular graphene provides an attractive man‐made artificial system to realize designer Dirac fermions with exotic properties and significant implications in electronics/spintronics, but its large‐scale fabrication remains a challenge as the available approach involves molecule‐by‐molecule manipulation of CO on a metal surface using a scanning tunneling microscopy tip. Here, we propose the epitaxial growth of molecular graphene on metal surface alloy, where CO molecules could be naturally self‐assembled into a hexagonal lattice. Via high‐throughput first‐principles calculations, the adsorption behaviors of CO on 30 surface alloys Cu 2 M (M represents the alloyed element) with a ()‐ R 30° superstructure on Cu(111) is explored. By systematically analyzing the structures, energetic and electronic properties of the adsorbed systems with different CO coverages, three surface alloys, Cu 2 Zn, Cu 2 Ga, and Cu 2 Ge, on which molecular graphene can be spontaneously formed, are successfully screened out. Remarkably, the self‐assembled molecular graphene is featured by an effective four‐band model involving the molecular (, ) orbitals of CO on a hexagonal lattice, leading to quantum spin Hall effect. This work paves an avenue for the large‐scale growth of artificial graphene, which should stimulate immediate interest among experimentalists in the synthesis, characterization, and implementation of topological states for dissipationless transport and quantum computing.