Solid substrates often induce non-uniform strain and doping in graphene monolayer, therefore altering the intrinsic properties of graphene, reducing its charge carrier mobilities and, consequently, the overall electrical performance. Here, we exploit confocal Raman spectroscopy to study graphene directly free-floating on the surface of water, and show that liquid supports relief the preexisting strain, have negligible doping effect and restore the uniformity of the properties throughout the graphene sheet. Such an effect originates from the structural adaptability and flexibility, lesser contamination and weaker intermolecular bonding of liquids compared to solid supports, independently of the chemical nature of the liquid. Moreover, we demonstrate that water provides a platform to study and distinguish chemical defects from substrate-induced defects, in the particular case of hydrogenated graphene. Liquid supports, thus, are advantageous over solid supports for a range of applications, particularly for monitoring changes in the graphene structure upon chemical modification.

中文翻译：

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液体松弛并统一了石墨烯中的应变。

固体基材通常会在石墨烯单层中引起不均匀的应变和掺杂，因此会改变石墨烯的内在特性，从而降低其电荷载流子迁移率，进而降低总体电性能。在这里，我们利用共聚焦拉曼光谱研究了在水表面直接自由浮动的石墨烯，并显示液体支持物可以缓解先前存在的应变，具有可忽略不计的掺杂效果，并可以恢复整个石墨烯片材性能的均匀性。这种效果源自与固体支持物相比，液体的结构适应性和柔性，较少的污染和较弱的分子间键合，而与液体的化学性质无关。此外，我们证明了水为研究和区分化学缺陷与底物诱导的缺陷提供了一个平台，在氢化石墨烯的特殊情况下。因此，对于一系列应用，尤其对于监测化学改性后石墨烯结构的变化而言，液体载体优于固体载体。