Precise and Ultrafast Molecular Sieving Through Graphene Oxide Membranes
Precise and Ultrafast Molecular Sieving Through Graphene Oxide Membranes
复制标题
通过氧化石墨烯膜进行精确、超快的分子筛分
DOI：
10.1126/science.1245711
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发表时间：
2014-02-14
期刊：
影响因子：
56.9
通讯作者：
Nair, R. R.
中科院分区：
文献类型：
--
作者：
Joshi, R. K.;Carbone, P.;Nair, R. R.
氧化石墨烯膜只允许非常小的水合分子和离子以加速的运输速率通过。石墨烯基材料可以具有定义良好的纳米孔，并且可以在其中表现出低摩擦水流动，使其特性对过滤和分离感兴趣。我们研究了通过真空过滤氧化石墨烯悬浮液制备的微米厚层压板的渗透性。层压板在干燥状态下是真空密封的，但如果浸入水中，就像分子筛一样，阻挡所有水合半径大于4.5埃的溶质。较小的离子通过膜的速度比预期的简单扩散快几千倍。我们认为，这种行为是由纳米毛细血管网络引起的，这些网络在水合状态下打开，只接受适合的物种。这种异常快速的渗透是由于石墨烯毛细血管内的离子受到类似毛细血管的高压作用。基于石墨烯的膜可以同时阻止非常小的分子通过，同时允许水快速渗透。Joshi等人（第752页，参见Mi的观点）研究了水溶液中离子和中性分子通过氧化石墨烯（GO）膜的渗透。水合半径小于0.45纳米的小离子通过氧化石墨烯膜的速度比根据扩散理论预测的要快几个数量级。分子动力学模拟表明，氧化石墨烯膜可以吸引高浓度的小离子进入膜内，这可能解释了离子的快速传输。
Graphene oxide membranes allow only very small hydrated molecules and ions to pass with an accelerated transport rate. [Also see Perspective by Mi] Graphene-based materials can have well-defined nanometer pores and can exhibit low frictional water flow inside them, making their properties of interest for filtration and separation. We investigate permeation through micrometer-thick laminates prepared by means of vacuum filtration of graphene oxide suspensions. The laminates are vacuum-tight in the dry state but, if immersed in water, act as molecular sieves, blocking all solutes with hydrated radii larger than 4.5 angstroms. Smaller ions permeate through the membranes at rates thousands of times faster than what is expected for simple diffusion. We believe that this behavior is caused by a network of nanocapillaries that open up in the hydrated state and accept only species that fit in. The anomalously fast permeation is attributed to a capillary-like high pressure acting on ions inside graphene capillaries. On the Fast Track Membranes based on graphene can simultaneously block the passage of very small molecules while allowing the rapid permeation of water. Joshi et al. (p. 752; see the Perspective by Mi) investigated the permeation of ions and neutral molecules through a graphene oxide (GO) membrane in an aqueous solution. Small ions, with hydrated radii smaller than 0.45 nanometers, permeated through the GO membrane several orders of magnitude faster than predicted, based on diffusion theory. Molecular dynamics simulations revealed that the GO membrane can attract a high concentration of small ions into the membrane, which may explain the fast ion transport.