Designing Angstrom-Scale Asymmetric MOF-on-MOF Cavities for High Monovalent Ion Selectivity
Designing Angstrom-Scale Asymmetric MOF-on-MOF Cavities for High Monovalent Ion Selectivity
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DOI：
10.1002/adma.202107878
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发表时间：
2022-01-20
影响因子：
29.4
通讯作者：
Razmjou, Amir
中科院分区：
文献类型：
--
作者：
Abdollahzadeh, Mojtaba;Chai, Milton;Razmjou, Amir
生物离子通道具有埃尺度的非对称空腔结构，这是实现高效分离和传感水资源中碱金属离子的关键。清洁能源的未来和锂基储能系统严重依赖于高效的离子分离。然而，人工重建如此复杂的生物结构在技术上具有挑战性。在这里，一个高度可调的设计概念被引入到制造单价离子选择性膜与不对称的亚纳米孔中的能量障碍植入。能量屏障作用于离子运动，其保持目标离子，同时促进竞争离子的传输。该膜由双层金属有机框架（MOF-on-MOF）组成，具有6至3.4埃的可通过腔结构。离子电流测量显示出超过100的前所未有的离子电流整流比，对K+/Li+和Na+/ Li+的选择性比分别为84和80（1.14 Li+ mol m（-2）h（-1））。此外，使用量子力学/分子力学，它表明，空间位阻和亲核截留诱导能量浪涌挡板的组合效应是负责膜的质子选择性和离子整流。这项工作展示了在开发单价离子选择性通道方面的惊人进展，并在传感，能量存储和分离技术方面具有意义。
Biological ion channels feature angstrom-scale asymmetrical cavity structures, which are the key to achieving highly efficient separation and sensing of alkali metal ions from aqueous resources. The clean energy future and lithium-based energy storage systems heavily rely on highly efficient ionic separations. However, artificial recreation of such a sophisticated biostructure has been technically challenging. Here, a highly tunable design concept is introduced to fabricate monovalent ion-selective membranes with asymmetric sub-nanometer pores in which energy barriers are implanted. The energy barriers act against ionic movements, which hold the target ion while facilitating the transport of competing ions. The membrane consists of bilayer metal-organic frameworks (MOF-on-MOF), possessing a 6 to 3.4-angstrom passable cavity structure. The ionic current measurements exhibit an unprecedented ionic current rectification ratio of above 100 with exceptionally high selectivity ratios of 84 and 80 for K+/Li+ and Na+/ Li+, respectively (1.14 Li+ mol m(-2) h(-1)). Furthermore, using quantum mechanics/molecular mechanics, it is shown that the combined effect of spatial hindrance and nucleophilic entrapment to induce energy surge baffles is responsible for the membrane's ultrahigh selectivity and ion rectification. This work demonstrates a striking advance in developing monovalent ion-selective channels and has implications in sensing, energy storage, and separation technologies.