Electronically Engineered Nanoporous Graphene*

Recent advances in the synthesis of graphene nanoribbons using on-surface bottom-up techniques have enabled fabrication of not only atomically well-defined one-dimensional structures, but also two-dimensional structures such as nanoporous graphenes. These are particularly interesting for applications due to their sieve-like topology. Here we present a new methodology for creating covalently connected, fully conjugated two-dimensional graphene structures through the utilization of cyclopentadiene (CP) moieties. CP elements exhibit a propensity to initiate fusion between nanoribbons and result in a two-dimensional structure with well-defined interface topology. The resulting new material is analyzed using scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and bond-resolved scanning tunneling microscopy (BRSTM). We observe emergent interface-localized electronic states that hybridize to yield a dispersive two-dimensional band of states at an energy inside the bandgap of an isolated GNR.