10:15 AM - 10:30 AM
[7a-C16-6] Two- to Three-dimensional Transition of Confined Water between Freestanding Graphene Sheets
Keywords:Graphene, Molecular dynamics, Confined Water
Recent discoveries of unusual water structure confined inside nano-structures lead to a possibility of an analysis of low-dimensional water properties, such as solubility and viscosity. Depending on thermal dynamics, bulk water can exist in several phases from gas, liquid, solid to polymorphous states. Confined water, however, could adopt new forms not seen in the open air, such as a new two-dimensional (2D) square ice trapped between two graphene sheets [1]: The recent experiment using the Transmission Electron Microscopy (TEM) has shown the anomalous water phase with the square ice structure, confined between two graphene sheets. Further theoretical investigations using classical molecular dynamics simulations have suggested that the lateral pressure arising from Van der Waals attraction between the graphene sheets is the main factor for the square ice formation. In the case of confined water, besides temperature and pressure, additional variables such as the confinement geometry might play an important role in determining the structure of confined water. In most of theoretical approaches, the confined water between graphene sheets has been simulated using nano-capillary model formed by two parallel rigid graphene sheets. However, for a naturally flexible material such as graphene, a soft confinement is more likely to occur, thus it is essential to investigate the effect of elasticity of graphene.
In this study, we employed classical molecular dynamics simulations with Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential to produce soft-confining property of graphene. We discovered the solid-like structures of water molecules encapsulated between two freestanding graphene sheets at room temperature (300K).
Soft confinement of water molecules between two freestanding graphene sheets resulted in various solid-like structure ranging from two-dimensional to three-dimensional structure. Small amount of water encapsulation lead to a layered two-dimensional form with the square ice structure. On the other hand, with increasing water amounts, the water structure changed from two-dimensional layered to three–dimensional flying saucer-like form with the square ice intra-layer structure. The effect of flexibility of graphene on its confining ability will be discussed in the presentation.
In this study, we employed classical molecular dynamics simulations with Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential to produce soft-confining property of graphene. We discovered the solid-like structures of water molecules encapsulated between two freestanding graphene sheets at room temperature (300K).
Soft confinement of water molecules between two freestanding graphene sheets resulted in various solid-like structure ranging from two-dimensional to three-dimensional structure. Small amount of water encapsulation lead to a layered two-dimensional form with the square ice structure. On the other hand, with increasing water amounts, the water structure changed from two-dimensional layered to three–dimensional flying saucer-like form with the square ice intra-layer structure. The effect of flexibility of graphene on its confining ability will be discussed in the presentation.