Graphdiyne (GDY) is an appealing two-dimensional carbon material, but the on-surface synthesis of a single layer remains challenging. Demetalation of well-crystalline metal acetylide networks, though in its infancy, provides a new avenue to on-surface synthesized GDY substructures. In spite of the synthetic efforts and theoretical concerns, there are few reports steeped in elaborate characterization of the electronic influence of metalation. In this context, we focused on the surface supported Au-bis-acetylide network, which underwent demetalation after further annealing to form hydrogen-substituted GDY. We made a comprehensive study on the geometric structure and electronic structure and the corresponding demetalized structure on Au(111) through STM, noncontact atomic force microscopy (nc-AFM), scanning tunneling spectroscopy (STS), and density functional theory (DFT) simulations. The bandgap of the Au-bis-acetylide network on Au(111) is measured to be 2.7 eV, while the bandgap of a fully demetalized Au-bis-acetylide network is estimated to be about 4.1 eV. Our findings reveal that the intercalated Au adatoms are positioned closer to the metal surface compared with the organic skeletons, facilitating electronic hybridization between the surface state and unoccupied frontier molecular orbitals of organic components. This leads to an extended conjugation through Au-bis-acetylene bonds, resulting in a reduced bandgap.

中文翻译：

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Au(111) 上 Au-双乙炔网络的扫描隧道光谱研究：金属有机杂化的影响

石墨炔（GDY）是一种有吸引力的二维碳材料，但单层的表面合成仍然具有挑战性。结晶良好的金属乙炔化物网络的脱金属虽然还处于起步阶段，但为表面合成 GDY 亚结构提供了一条新途径。尽管进行了合成努力和理论关注，但很少有报告详细描述金属化的电子影响。在这种情况下，我们重点关注表面支撑的 Aubis-乙炔网络，该网络在进一步退火后发生脱金属，形成氢取代的 GDY。我们通过STM、非接触原子力显微镜(nc-AFM)、扫描隧道光谱(STS)和密度泛函理论(DFT)模拟对Au(111)的几何结构和电子结构以及相应的脱金属结构进行了全面的研究。 Au(111)上Aubis-乙炔网络的带隙测量为2.7 eV，而完全脱金属的Aubis-乙炔网络的带隙估计约为4.1 eV。我们的研究结果表明，与有机骨架相比，插层金吸附原子的位置更靠近金属表面，有利于有机组分的表面态和未占据的前沿分子轨道之间的电子杂化。这导致通过 Aubis-乙炔键延长共轭，导致带隙减小。