论文标题
表面亲水性和水合对超冷水旋转阳光在石墨烯氧化石墨烯表面上的影响
Influence of Surface Hydrophilicity and Hydration on the Rotational Relaxation of Supercooled Water on Graphene Oxide Surfaces
论文作者
论文摘要
生物分子和无机固体中存在的水合或界面水已被证明在过冷时表现出动态过渡。然而，没有探索对潜在的表面亲水性的程度以及在动态跃迁上的亲水/疏水斑的局部分布。在这里，我们使用带有TIP4P/2005水模型的分子动力学模拟来研究石墨烯表面上界面水的翻译和旋转弛豫动力学。这项研究的目的是研究表面化学的影响以及水合对深层过冷区域中界面水旋转过渡（GO）表面的旋转跃迁的影响。我们考虑了三个基于石墨烯的表面。在条纹拓扑，完全氧化的表面和原始石墨烯表面的氧化和原始石墨烯区相等比例的GO表面。界面水的偶极子松弛时间在210-298 k的温度范围内分别显示出强到紧，坚固，强度到突变的过渡。在所有这些情况下，在高水化的情况下，界面水与具有散装特性的厚水膜并存。为了研究大量水对动态跃迁的影响，我们模拟了一个低的水合状态，其中仅存在绑定的水（地表水）在GO表面上，发现地表水在GO和完全氧化的表面上的旋转弛豫显示出一种单一的Arrhenius行为。我们的结果表明，不仅表面亲水性的局部程度在确定超冷时水分子探索的能量景观中起作用，而且大量水的存在也会调节动态过渡。
Hydration or interfacial water present in biomolecules and inorganic solids have been shown to exhibit a dynamical transition upon supercooling. However, an understanding of the extent of the underlying surface hydrophilicity as well as the local distribution of hydrophilic/hydrophobic patches on the dynamical transition is unexplored. Here, we use molecular dynamics simulations with a TIP4P/2005 water model to study translational and rotational relaxation dynamics of interfacial water on graphene surfaces. The purpose of this study is to investigate the influence of both surface chemistry as well as the extent of hydration on the rotational transitions of interfacial water on graphene oxide (GO) surfaces in the deeply supercooled region. We have considered three graphene-based surfaces; a GO surface with equal proportions of oxidized and pristine graphene regions in a striped topology, a fully oxidized surface and a pristine graphene surface. The dipole relaxation time of interfacial water shows a strong-to-strong, strong, and a fragile-to-strong transition on these surfaces, respectively, in the temperature range of 210-298 K. In contrast, bulk water shows a fragile-to-strong transition upon supercooling. In all these cases at high hydration, interfacial water co-exists with a thick water film with bulk-like properties. To investigate the influence of bulk water on dynamical transitions, we simulated a low hydration regime where only bound water (surface water) is present on the GO surfaces and found that the rotational relaxation of surface water on both the GO and fully oxidized surfaces show a single Arrhenius behavior. Our results indicate that not only does the local extent of surface hydrophilicity play a role in determining the energy landscape explored by the water molecules upon supercooling, but the presence of bulk water also modulates the dynamic transition.
