Controlled transport of water molecules through membranes and capillaries is important in areas as diverse as water purification and healthcare technologies1–7. Previous attempts to control water permeation through membranes (mainly polymeric ones) have concentrated on modulating the structure of the membrane and the physicochemical properties of its surface by varying the pH, temperature or ionic strength3,8. Electrical control over water transport is an attractive alternative; however, theory and simulations9–14 have often yielded conflicting results, from freezing of water molecules to melting of ice14–16 under an applied electric field. Here we report electrically controlled water permeation through micrometre-thick graphene oxide membranes17–21. Such membranes have previously been shown to exhibit ultrafast permeation of water17,22 and molecular sieving properties18,21, with the potential for industrial-scale production. To achieve electrical control over water permeation, we create conductive filaments in the graphene oxide membranes via controllable electrical breakdown. The electric field that concentrates around these current-carrying filaments ionizes water molecules inside graphene capillaries within the graphene oxide membranes, which impedes water transport. We thus demonstrate precise control of water permeation, from ultrafast permeation to complete blocking. Our work opens up an avenue for developing smart membrane technologies for artificial biological systems, tissue engineering and filtration.The rapid water transport through graphene oxide membranes can be switched off by introducing localized electric fields within the membranes that ionize surrounding water molecules and thus block transport.

中文翻译：

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电控水通过氧化石墨烯膜渗透

水分子通过膜和毛细管的受控传输在水净化和医疗保健技术等不同领域中很重要1-7。以前控制水通过膜（主要是聚合物膜）渗透的尝试集中在通过改变 pH 值、温度或离子强度来调节膜的结构及其表面的物理化学性质 3,8。对水上运输的电气控制是一个有吸引力的替代方案；然而，理论和模拟 9-14 经常产生相互矛盾的结果，从水分子的冻结到外加电场下冰的融化 14-16。在这里，我们报告了通过微米厚的氧化石墨烯膜的电控水渗透 17-21。此类膜先前已被证明具有超快的水渗透性 17，22 和分子筛分特性 18,21，具有工业规模生产的潜力。为了实现对水渗透的电气控制，我们通过可控的电击穿在氧化石墨烯膜中创建导电细丝。集中在这些载流细丝周围的电场使氧化石墨烯膜内石墨烯毛细管内的水分子电离，从而阻碍水的传输。因此，我们展示了对水渗透的精确控制，从超快渗透到完全阻塞。我们的工作为开发用于人工生物系统、组织工程和过滤的智能膜技术开辟了道路。