Liu Jian, Lai Chia-Yun, Zhang Yu-Yang, Chiesa Matteo, Pantelides Sokrates T
Department of Physics and Astronomy, Vanderbilt University Tennessee 37235 USA
Laboratory for Energy and Nano-Sciences, Khalifa University of Science and Technology Abu Dhabi United Arab Emirates.
RSC Adv. 2018 May 8;8(30):16918-16926. doi: 10.1039/c8ra03509a. eCollection 2018 May 3.
Wetting phenomena are ubiquitous and impact a wide range of applications. Simulations so far have largely relied on classical potentials. Here, we report the development of an approach that combines density-functional theory (DFT)-based calculations with classical wetting theory that allows practical but sufficiently accurate determination of the water contact angle (WCA). As a benchmark, we apply the approach to the graphene and graphite surfaces that recently received considerable attention. The results agree with and elucidate the experimental data. For metal-supported graphene where electronic interactions play a major role, we demonstrate that doping of graphene by the metal substrate significantly alters the wettability. In addition to theory, we report new experimental measurements of the WCA and the force of adhesion that corroborate the theoretical results. We demonstrate a correlation between the force of adhesion and WCA, and the use of the atomic force microscope (AFM) technique as an alternative measure for wettability at the nanoscale. The present work not only provides a detailed understanding of the wettability of graphene, including the role of electrons, but also sets the stage for studying the wettability alteration mechanism when sufficiently accurate force fields may not be available.
润湿现象无处不在，影响着广泛的应用。迄今为止，模拟主要依赖于经典势。在此，我们报告了一种将基于密度泛函理论（DFT）的计算与经典润湿理论相结合的方法的开发，该方法能够实际且足够准确地确定水接触角（WCA）。作为基准，我们将该方法应用于最近备受关注的石墨烯和石墨表面。结果与实验数据相符并对其进行了阐释。对于电子相互作用起主要作用的金属支撑石墨烯，我们证明金属衬底对石墨烯的掺杂会显著改变润湿性。除了理论，我们还报告了新的水接触角和粘附力实验测量结果，这些结果证实了理论结果。我们展示了粘附力与水接触角之间的相关性，以及使用原子力显微镜（AFM）技术作为纳米尺度润湿性的替代测量方法。本工作不仅详细地解释了石墨烯的润湿性，包括电子的作用，还为在可能没有足够精确的力场时研究润湿性改变机制奠定了基础。
