Robust ultrathin nanoporous MOF membrane with intra-crystalline defects for fast water transport

Xueling Wang,Fenglin Yang,Chuyang Y Tang,Yingchao Dong,Xie Quan,Michael D Guiver,Tiezheng Tong,Li-Chiang Lin,Kuo Sun,Qiang Lyu

doi:10.1038/s41467-021-27873-6

Xueling Wang, Fenglin Yang + Show 8 more

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https://doi.org/10.1038/s41467-021-27873-6

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Rational design of high-performance stable metal–organic framework (MOF) membranes is challenging, especially for the sustainable treatment of hypersaline waters to address critical global environmental issues. Herein, a molecular-level intra-crystalline defect strategy combined with a selective layer thinning protocol is proposed to fabricate robust ultrathin missing-linker UiO-66 (ML-UiO-66) membrane to enable fast water permeation. Besides almost complete salt rejection, high and stable water flux is achieved even under long-term pervaporation operation in hash environments, which effectively addresses challenging stability issues. Then, detailed structural characterizations are employed to identify the type, chemical functionality, and density of intra-crystalline missing-linker defects. Moreover, molecular dynamics simulations shed light on the positive atomistic role of these defects, which are responsible for substantially enhancing structural hydrophilicity and enlarging pore window, consequently allowing ultra-fast water transport via a lower-energy-barrier pathway across three-dimensional sub-nanochannels during pervaporation. Unlike common unfavorable defect effects, the present positive intra-crystalline defect engineering concept at the molecular level is expected to pave a promising way toward not only rational design of next-generation MOF membranes with enhanced permeation performance, but additional water treatment applications.

Highlights

Rational design of high-performance stable metal–organic framework (MOF) membranes is challenging, especially for the sustainable treatment of hypersaline waters to address critical global environmental issues
Most MOFs are not stable in aqueous media applications such as membrane separation. Despite their enhanced flux compared with zeolite membranes, current water-stable MOF membranes exhibit moderate flux[25,26], which needs to be further improved for future large-scale applications
Further enhancing water flux is more challenging, which calls for the rational design of MOF membrane structures at the molecular or atomic level

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Rational design of high-performance stable metal–organic framework (MOF) membranes is challenging, especially for the sustainable treatment of hypersaline waters to address critical global environmental issues. Besides almost complete salt rejection, high and stable water flux is achieved even under long-term pervaporation operation in hash environments, which effectively addresses challenging stability issues. Unlike common unfavorable defect effects, the present positive intra-crystalline defect engineering concept at the molecular level is expected to pave a promising way toward rational design of nextgeneration MOF membranes with enhanced permeation performance, but additional water treatment applications. Due to the presence of various detrimental species in real waters, membrane fouling, scaling, and wetting often result in performance degradation of MD, especially over long-term operation[13,14,15] These shortcomings motivate us to develop alternative technologies. Further enhancing water flux is more challenging, which calls for the rational design of MOF membrane structures at the molecular or atomic level

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