Tunable Pore Size from Sub-Nanometer to a Few Nanometers in Large-Area Graphene Nanoporous Atomically Thin Membranes
Tunable Pore Size from Sub-Nanometer to a Few Nanometers in Large-Area Graphene Nanoporous Atomically Thin Membranes
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DOI：
10.1021/acsami.1c06243
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发表时间：
2021-06-16
影响因子：
9.5
通讯作者：
Wang, Luda
中科院分区：
文献类型：
--
作者：
Chen, Xiaobo;Zhang, Shengping;Wang, Luda
膜是化学净化、生物分离和海水淡化的关键部件。传统的聚合物膜普遍需要在渗透和选择性之间进行权衡，这严重影响了膜的分离性能。纳米多孔原子薄膜(NaTm)，如石墨烯NaTm，有可能打破这种平衡。由于其独特的二维结构和潜在的纳米孔结构可控性，通过分子筛分有望获得优异的选择性，同时实现最终的渗透。然而，在石墨烯膜的概念验证演示和可扩展分离应用之间存在着严重的选择性差异。在这篇文章中，我们提供了一种可能的解决方案，通过连续两次等离子体处理分别调节孔密度和孔大小来缩小这种差异。我们证明，通过缩小孔径分布，可以大大提高石墨烯膜的选择性。首次将低能量的Ar等离子体用于石墨烯中高密度缺陷的形核。然后利用受控氧等离子体将缺陷选择性地放大到所需尺寸的纳米孔中。这种方法具有可扩展性，制备的1 cm(2)亚纳米孔石墨烯纳米管可以分离氯化钾和阿卢拉红，选择性为10(4)，渗透系数为1.1×10(-6)m S(-1)。NAFM中的孔可以进一步从气体选择的亚纳米孔调整到几个纳米尺寸。所制备的NaTMS在CO2和N-2之间的选择性为35。随着放大时间的延长，溶菌酶和牛血清白蛋白之间的选择性也可以达到21.2，透过率大约是商业透析膜的4倍。本研究为实现从亚纳米级气体分离或海水淡化到几纳米级透析的不同分离过程提供了一种孔径可调、孔径分布窄的纳米纳米膜的解决方案。
Membranes are key components in chemical purification, biological separation, and water desalination. Traditional polymeric membranes are subjected to a ubiquitous trade-off between permeance and selectivity, which significantly hinders the separation performance. Nanoporous atomically thin membranes (NATMs), such as graphene NATMs, have the potential to break this trade-off. Owing to their uniqueness of two-dimensional structure and potential nanopore structure controllability, NATMs are expected to have outstanding selectivity through molecular sieving while achieving ultimate permeance at the same time. However, a drastic selectivity discrepancy exists between the proof-of-concept demonstrations and scalable separation applications in graphene membranes. In this paper, we offer a possible solution to narrow this discrepancy by tuning the pore density and pore size separately with two successive plasma treatments. We demonstrate that by narrowing the pore size distribution, the selectivity of graphene membranes can be greatly increased. Low-energy argon plasma is first applied to nucleate high density of defects in graphene. Controlled oxygen plasma is then utilized to selectively enlarge the defects into nanopores with desired sizes. This method is scalable, and the fabricated 1 cm(2) graphene NATMs with sub-nanometer pores can separate KCl and Allura Red with a selectivity of 10(4) and a permeance of 1.1 x 10(-6) m s(-1). The pores in NATMs can be further tuned from gas-selective sub-nanometer pores to a few nanometer size. The fabricated NATMs show a selectivity of 35 between CO2 and N-2. With longer enlargement time, a selectivity of 21.2 between a lysozyme and bovine serum albumin can also be achieved with roughly four times higher permeance than that of a commercial dialysis membrane. This research offers a solution to realize NATMs of tunable pore size with a narrow pore size distribution for different separation processes from sub-nanometer in gas separation or desalination to a few nanometers in dialysis.