Fan Hongwei, Peng Manhua, Strauss Ina, Mundstock Alexander, Meng Hong, Caro Jürgen
Institute of Physical Chemistry and Electrochemistry, Leibniz Universität Hannover, Callinstraße 3A, 30167, Hannover, Germany.
Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstrasse 2, 30167, Hannover, Germany.
Nat Commun. 2021 Jan 4;12(1):38. doi: 10.1038/s41467-020-20298-7.
Covalent organic frameworks (COFs) are promising materials for advanced molecular-separation membranes, but their wide nanometer-sized pores prevent selective gas separation through molecular sieving. Herein, we propose a MOF-in-COF concept for the confined growth of metal-organic framework (MOFs) inside a supported COF layer to prepare MOF-in-COF membranes. These membranes feature a unique MOF-in-COF micro/nanopore network, presumably due to the formation of MOFs as a pearl string-like chain of unit cells in the 1D channel of 2D COFs. The MOF-in-COF membranes exhibit an excellent hydrogen permeance (>3000 GPU) together with a significant enhancement of separation selectivity of hydrogen over other gases. The superior separation performance for H/CO and H/CH surpasses the Robeson upper bounds, benefiting from the synergy combining precise size sieving and fast molecular transport through the MOF-in-COF channels. The synthesis of different combinations of MOFs and COFs in robust MOF-in-COF membranes demonstrates the versatility of our design strategy.
共价有机框架（COFs）是用于先进分子分离膜的有前景的材料，但其宽纳米尺寸的孔阻碍了通过分子筛进行选择性气体分离。在此，我们提出了一种“COF包封MOF”的概念，用于在负载的COF层内限制金属有机框架（MOFs）的生长，以制备“COF包封MOF”膜。这些膜具有独特的“COF包封MOF”微/纳米孔网络，这可能是由于在二维COF的一维通道中形成了作为珍珠串状晶胞链的MOFs。“COF包封MOF”膜表现出优异的氢气渗透率（>3000 GPU），同时氢气对其他气体的分离选择性显著提高。H₂/CO和H₂/CH₄的卓越分离性能超过了罗伯逊上限，这得益于精确尺寸筛分和通过“COF包封MOF”通道的快速分子传输相结合的协同作用。在坚固的“COF包封MOF”膜中合成不同组合的MOFs和COFs证明了我们设计策略的通用性。
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