Controlling Interlayer Spacing of Graphene Oxide Membranes by External Pressure Regulation
Controlling Interlayer Spacing of Graphene Oxide Membranes by External Pressure Regulation
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通过外部压力调节控制氧化石墨烯膜的层间距
DOI：
10.1021/acsnano.8b04187
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发表时间：
2018-09-01
期刊：
影响因子：
17.1
通讯作者：
Li, Zhanjun
中科院分区：
文献类型：
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作者：
Li, Wanbin;Wu, Wufeng;Li, Zhanjun
氧化石墨烯（GO）膜因其在各种应用中的出色性能而受到广泛关注，特别是在水净化方面。然而，由于在水和极性有机溶剂中的膨胀导致层间通道的增加，GO膜通常对亚纳米尺寸的分子具有较差的截留能力。如何在埃水平上控制GO膜的传输通道是一个具有重大科学性和实用性的问题。在此，报道了外部压力调节（EPR）的概念，用于抑制GO膨胀并精确控制其层间距。由于各向异性GO薄膜仅在垂直方向膨胀，因此可以通过外部单向反向力来操纵层间通道。基于这一理念，设计了带有GO膜的EPR系统，通过调节高分辨率的外部压力来实现海水淡化。在错流过滤中，压缩的GO膜表现出高KCl、NaCl和CaCl2截留率，分别为94%、97%和98%，并在2 bar的低进料压力下具有高达25 L m(-2) h(-1)的大水渗透率，尽管基底孔上方超薄GO层的半自由空间膨胀会恶化脱盐率。我们的工作提供了一种简单的物理策略来调整二维纳米片制造的膜的层间距，以实现所需的过滤能力。
Graphene oxide (GO) membranes have been attracting numerous attention due to their impressive performance in various applications, especially in water purification. However, because the swelling in water and polar organic solvents causes the increase of interlayer channels, GO membranes usually possess inferior rejection for subnanometer-sized molecules. How to control the transport channels of GO membranes at angstrom level is a significantly scientific and practical issue. Herein, a concept of external pressure regulation (EPR) is reported for restraining GO swelling and controlling its interlayer spacing precisely. Since anisotropic GO films only swell at vertical direction, the interlayer channels can be manipulated by externally unidirectional reverse force. Based on this concept, an EPR system with GO membranes is designed for water desalination by adjusting the external pressure that has high resolution. In cross-flow filtration, the compressed GO membranes show high KCl, NaCl, and CaCl2 rejections of 94%, 97%, and 98%, respectively, accompanied by large water permeance up to 25 L m(-2) h(-1) under low feed pressure of 2 bar, despite the fact that the semi-free spatial swelling of ultrathin GO layer above the substrate pores can deteriorate salt rejection. Our work provides a straightforward physical strategy to adjust the interlayer spacing of the membranes fabricated by two-dimensional nanosheets for achieving desired filtration capacity.