Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca , via Cozzi 55, 20125 Milano, Italy.
ACS Appl Mater Interfaces. 2017 Sep 6;9(35):29932-29941. doi: 10.1021/acsami.7b06633. Epub 2017 Aug 24.
The presence of defects in the graphenic layers deposited on metal surfaces modifies the nature of the interaction. Unsaturated carbon atoms, due to vacancies in the lattice, form strong organometallic bonds with surface metal atoms that highly enhance the binding energy between the two materials. We investigate by means of a wide set of dispersion-corrected density functional theory calculations how such strong chemical bonds affect both the electronic properties of these hybrid interfaces and the chemical reactivity with water, which is commonly present in the working conditions. We compare different metal substrates (Cu vs Pt) that present a different type of interaction with graphene and with defective graphene. This comparative analysis allows us to unravel the controlling factors of water reactivity, the role played by the carbon vacancies and by the confinement or "graphene cover effect". Water is capable of breaking the C-Cu bond by dissociating at the undercoordinated carbon atom of the vacancy, restoring the weak van der Waals type of interaction between the two materials that allows for an easy detachment of graphene from the metal, but the same is not true in the case of Pt, where C-Pt bonds are much stronger. These conclusions can be used to rationalize water reactivity at other defective graphene/metal interfaces.
在金属表面沉积的石墨层中存在缺陷会改变相互作用的性质。由于晶格中的空位，不饱和碳原子与表面金属原子形成强的有机金属键，极大地增强了两种材料之间的结合能。我们通过广泛的色散校正密度泛函理论计算来研究这些强化学键如何影响这些杂化界面的电子性质以及与水的化学反应性，因为水通常存在于工作条件中。我们比较了不同的金属基底（Cu 对 Pt），它们与石墨烯和有缺陷的石墨烯具有不同的相互作用类型。这种对比分析使我们能够揭示水反应性的控制因素、碳空位的作用以及限制或“石墨烯覆盖效应”的作用。水能够通过在空位的配位不足的碳原子处离解来打破 C-Cu 键，恢复两种材料之间的弱范德华类型相互作用，从而使石墨烯很容易从金属上脱离，但在 Pt 的情况下则不然，因为 C-Pt 键强得多。这些结论可用于合理化其他有缺陷的石墨烯/金属界面的水反应性。
