Hydrogen functionalization of graphene by exposure to vibrationally excited H₂ molecules is investigated by combined scanning tunneling microscopy, high-resolution electron energy loss spectroscopy, X-ray photoelectron spectroscopy measurements, and density functional theory calculations. The measurements reveal that vibrationally excited H₂ molecules dissociatively adsorb on graphene on Ir(111) resulting in nanopatterned hydrogen functionalization structures. Calculations demonstrate that the presence of the Ir surface below the graphene lowers the H₂ dissociative adsorption barrier and allows for the adsorption reaction at energies well below the dissociation threshold of the H–H bond. The first reacting H₂ molecule must contain considerable vibrational energy to overcome the dissociative adsorption barrier. However, this initial adsorption further activates the surface resulting in reduced barriers for dissociative adsorption of subsequent H₂ molecules. This enables functionalization by H₂ molecules with lower vibrational energy, yielding an avalanche effect for the hydrogenation reaction. These results provide an example of a catalytically active graphene-coated surface and additionally set the stage for a re-interpretation of previous experimental work involving elevated H₂ background gas pressures in the presence of hot filaments.

中文翻译：

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令人兴奋的H2分子对石墨烯的功能化作用。

通过组合扫描隧道显微镜，高分辨率电子能量损失谱，X射线光电子能谱测量和密度泛函理论计算，研究了石墨烯通过暴露于振动激发的H ₂分子而得到的氢官能化。测量结果表明，振动激发的H ₂分子解离吸附在Ir（111）上的石墨烯上，从而形成纳米图案的氢官能化结构。计算表明，石墨烯下方Ir表面的存​​在降低了H _2的离解吸附势垒，并允许在远低于H–H键的离解阈值的能量下发生吸附反应。第一个反应的H ₂分子必须包含相当大的振动能才能克服离解性吸附障碍。但是，这种初始吸附进一步活化了表面，从而降低了对随后的H ₂分子进行解离吸附的势垒。这使得能够通过具有较低振动能的H ₂分子进行官能化，从而为氢化反应产生雪崩效应。这些结果提供了一个具有催化活性的石墨烯涂层表面的实例，并为重新解释先前的实验工作奠定了基础，该实验涉及在存在热丝的情况下涉及升高的H ₂背景气体压力。