Water confined in two-dimensional channels exhibits unique properties, such as rich morphology, specific phase transition and a low dielectric constant. In this work, molecular dynamics simulations have been used to study the water transport in two-dimensional graphene channels. The structures and dynamics of water under confinement show strong dependence on the channel length and thickness of the channels. In particular, there exists a critical channel length beyond which monolayer water forms square-like ice structures, leading to the rapid decrease in water flow that eventually ceases completely. The water flow for double-layer and three-layer systems exhibits a similar exponential decay but does not reach zero. The translocation time exhibits an excellent power-law behavior with an increase in the channel length, accounting for the exponential flow decay. The radial distribution function confirms the length-dependent liquid-to-ice phase transition of monolayer water and the liquid states for double-layer and three-layer systems. The formation of monolayer ice can be further supported by the increasing barriers in the potential of mean force and specific dipole distributions. Furthermore, the melting temperature of monolayer ice increases significantly with the increase in the channel length that can also be close to or even exceeds the boiling point at atmospheric pressure. These findings provide new physical insights into the extraordinary length-dependent water behaviors and suggest future experimental studies on high-temperature ice through the size control in nanochannels.

中文翻译：

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通过石墨烯通道的水渗透长度相关


受限在二维通道中的水表现出独特的特性，例如丰富的形态、特定的相变和低介电常数。在这项工作中，分子动力学模拟已被用于研究二维石墨烯通道中的水传输。承压作用下水的结构和动力学对通道的长度和厚度有很强的依赖性。特别是，存在一个临界通道长度，超过该长度，单层水会形成方形冰结构，导致水流迅速减少，最终完全停止。双层和三层系统的水流表现出类似的指数衰减，但不会达到零。易位时间表现出出色的幂律行为，随着通道长度的增加，解释了指数流衰减。径向分布函数证实了单层水的长度依赖性液-冰相变以及双层和三层系统的液态。平均力和特定偶极子分布的可能性中不断增加的障碍可以进一步支持单层冰的形成。此外，单层冰的熔化温度随着通道长度的增加而显着增加，在大气压下也可能接近甚至超过沸点。这些发现为非凡的长度依赖性水行为提供了新的物理见解，并建议通过纳米通道中的尺寸控制对高温冰进行未来的实验研究。