Korea Institute for Advanced Study, Seoul, Korea.
Nano Lett. 2013 Aug 14;13(8):3930-5. doi: 10.1021/nl4020292. Epub 2013 Jul 19.
Water inside the low-dimensional carbon structures has been considered seriously owing to fundamental interest in its flow and structures as well as its practical impact. Recently, the anomalous perfect penetration of water through graphene oxide membrane was demonstrated although the membrane was impenetrable for other liquids and even gases. The unusual auxetic behavior of graphene oxide in the presence of water was also reported. Here, on the basis of first-principles calculations, we establish atomistic models for hybrid systems composed of water and graphene oxides revealing the anomalous water behavior inside the stacked graphene oxides. We show that formation of hexagonal ice bilayer in between the flakes as well as melting transition of ice at the edges of flakes are crucial to realize the perfect water permeation across the whole stacked structures. The distance between adjacent layers that can be controlled either by oxygen reduction process or pressure is shown to determine the water flow thus highlighting a unique water dynamics in randomly connected two-dimensional spaces.
由于对其流动和结构以及实际影响的基础研究，低维碳结构中的水受到了广泛关注。最近，尽管其他液体甚至气体都无法通过氧化石墨烯膜，但水却可以异常完美地通过该膜。也有报道称氧化石墨烯在存在水的情况下具有异常的负泊松比行为。在这里，我们基于第一性原理计算，为包含水和氧化石墨烯的混合体系建立了原子模型，揭示了堆叠氧化石墨烯内部的异常水行为。我们表明，在薄片之间形成六方冰双层以及在薄片边缘处冰的熔融转变对于实现整个堆叠结构中水的完美渗透是至关重要的。可以通过氧还原过程或压力来控制相邻层之间的距离，这表明它决定了水流，从而突出了在随机连接的二维空间中独特的水动力学。
