Synthesis of Graphene Nanosheets Containing Ultra-Narrow Nonplanar Nanopores on Surfaces

Introduction of twisted structures into low-dimensional graphene-based nanostructures has important ramifications on their inherent physical behavior. The fabrication of graphene derivatives with nonplanar characteristics remains challenging, especially for extended two-dimensional (2D) structures. Herein, we report the synthesis of a novel nonplanar porous [32]annulene graphene nanosheet that contains narrowest periodic nanopores and exhibits the highest negative curvature among one-dimensional (1D) and 2D graphene-based nanostructures synthesized up to date. The success is driven by the dissymmetrical debromination and regioselective coupling reactions of precursor molecules on a Au(111) surface, as corroborated by scanning tunneling microscopy (STM) and synchrotron radiation photoemission spectroscopy (SRPES). We characterize electronic properties of the porous [32]annulene graphene nanosheets with the aid of scanning tunneling spectroscopy (STS), and demonstrate the generation of a low-energy state resulting from the hole doping at the interface.