What Is the Contact Angle of Water on Graphene?
What Is the Contact Angle of Water on Graphene?
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DOI：
10.1021/la304645w
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发表时间：
2013-02-05
期刊：
影响因子：
3.9
通讯作者：
Leroy, Frederic
中科院分区：
文献类型：
--
作者：
Taherian, Fereshte;Marcon, Valentina;Leroy, Frederic
尽管实验和理论研究已经解决了石墨烯的润湿性问题，但水在孤立的石墨烯单层上的接触角的实际值仍然未知。虽然最近的实验文献表明水在石墨上的接触角在90-95度的范围内，但已经提出石墨烯上的接触角可以高达127度或与石墨相比适度增强。在使用经验力场的经典分子动力学模拟的支持下，我们提出了一个论证，表明127度的值是一个不切实际的估计，应该预期95-100度的值。我们的研究建立了石墨烯基表面上的水的粘附功的变化和单个水分子与这些表面之间的相互作用势之间的联系。我们表明，从石墨上的90度到石墨烯上的127度的接触角的变化意味着石墨的前两个碳层与水的相互作用能大致相同。这种情况与水和该基质之间相互作用的短程性质不相容。我们还表明，水和石墨烯基衬底之间的相互作用势能是主要的贡献的相对大小是独立的石墨烯层的数量的水的粘附的工作。我们介绍的想法，其余的贡献是熵的性质，并连接到水-基板相互作用能的波动。
Although experimental and theoretical studies have addressed the question of the wetting properties of graphene, the actual value of the contact angle of water on an isolated graphene monolayer remains unknown. While recent experimental literature indicates that the contact angle of water on graphite is in the range 90-95 degrees, it has been suggested that the contact angle on graphene may either be as high as 127 degrees or moderately enhanced in comparison with graphite. With the support of classical molecular dynamics simulations using empirical force-fields, we develop an argumentation to show that the value of 127 degrees is an unrealistic estimate and that a value of the order of 95-100 degrees should be expected. Our study establishes a connection between the variation of the work of adhesion of water on graphene-based surfaces and the interaction potential between individual water molecules and these surfaces. We show that a variation of the contact angle from 90 degrees on graphite to 127 degrees on graphene would imply that both of the first two carbon layers of graphite contribute approximately the same interaction energy with water. Such a situation is incompatible with the short-range nature of the interaction between water and this substrate. We also show that the interaction potential energy between water and the graphene-based substrates is the main contribution to the work of adhesion of water with a relative magnitude that is independent of the number of graphene layers. We introduce the idea that the remaining contribution is entropic in nature and is connected to the fluctuations in the water-substrate interaction energy.