Surfaces play a key role in determining material properties, and their importance is further magnified in the two-dimensional (2D) limit. Though monolayers are entirely composed of surfaces, there is no chemical approach to covalently address them without breaking intralayer bond. Here, we describe a 2D semiconductor that offers two unique features among 2D materials: structural hierarchy within the monolayer and surface reactive sites that enable functionalization. The 2D semiconductor is composed of a single layer of strongly interconnected Re6Se8 clusters arranged in an oblique lattice capped by substitutionally labile Cl atoms. We show that a simple ligand substitution strategy borrowed from traditional coordination chemistry can be used to modify the surface of the 2D material while preserving its internal structure. The potential generality of this approach establishes a promising route toward multifunctional 2D materials with tunable physical and chemical properties and may also facilitate better electrical top contact to 2D semiconductors.

中文翻译：

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具有可寻址表面的二维分层半导体

表面在决定材料特性方面起着关键作用，其重要性在二维 (2D) 极限中被进一步放大。尽管单层完全由表面组成，但没有化学方法可以在不破坏层内键的情况下共价寻址它们。在这里，我们描述了一种 2D 半导体，它在 2D 材料中提供了两个独特的特征：单层内的结构层次和能够实现功能化的表面反应位点。二维半导体由单层强烈互连的 Re6Se8 簇组成，排列在倾斜的晶格中，并被替换不稳定的 Cl 原子覆盖。我们表明，从传统配位化学中借用的简单配体取代策略可用于修饰二维材料的表面，同时保留其内部结构。