Engineering the MOF-based heterogenous subnanochannel membrane with a large pore geometry gradient. a) Schematic of the ZIF-8/PSSx@BANM with a tri-continuous pore structure from sub-microscale to sub-nanoscale and asymmetric charges. The thin ZIF-8/PSS MOF layer is characterized with angstrom-scale window-cavity structures and the BANM is composed of large sub-microscale stem channels and small nanoscale branched channels. b,c) SEM images showing that a ZIF-8/PSS layer can be continuously grown on the b) stem channel (ZIF-8/PSSx@s-BANM) and c) branched channel (ZIF-8/PSSx@b-BANM) sides of BANM. The pore sizes of stem and branched channels were ≈23 and ≈100 nm, respectively. The thickness of the ZIF-8/PSS layer was ≈300 nm. The total thickness of two heterogenous subnanochannel membranes was ≈19.3 µm.
工程化具有大孔徑幾何梯度的MOF基異質亞納米通道膜 a) ZIF-8/PSSx@BANM的示意圖，展示其從亞微米尺度到亞納米尺度的三連續孔結構及非對稱電荷分佈。薄層的ZIF-8/PSS MOF層具有埃級窗口-腔體結構，而BANM由大尺度的亞微米主幹通道和小尺度的納米分支通道組成。 b, c) 掃描電子顯微鏡（SEM）圖像顯示，ZIF-8/PSS層可以連續地生長在b) 主幹通道（ZIF-8/PSSx@s-BANM）和c) 分支通道（ZIF-8/PSSx@b-BANM）的BANM兩側。主幹通道和分支通道的孔徑分別約為23 nm和100 nm，ZIF-8/PSS層的厚度約為300 nm，而兩層異質亞納米通道膜的總厚度約為19.3 µm。

Major Contributions

1.Innovative Membrane Design with Tri-Continuous Pore Structure
We successfully developed a novel heterogeneous subnanochannel membrane (ZIF-8/PSS@BANM) featuring a tri-continuous pore structure with a large geometry gradient. This structure transitions from sub-nanoscale to nanoscale and sub-microscale, enabling enhanced ion selectivity, strong ionic rectification, and ultrafast ion transport in organic electrolyte solutions. This design overcomes the limitations of conventional membranes, such as poor ion selectivity and low conductance in organic solvents.

2.Record-Breaking Osmotic Power Conversion Efficiency
Our membrane achieved an unprecedented power density of approximately 50.5 W·m⁻² by mixing 2 m LiCl-methanol with pure methanol solutions. This performance is over 45 times higher than existing membranes, demonstrating the effectiveness of our design in harvesting osmotic power from organic solutions. The remarkable efficiency stems from amplified directional ion transport and strong ionic rectification facilitated by the angstrom-scale ZIF-8/PSS layer.

3.Breakthrough in Ion Transport Mechanisms
By integrating a negatively charged ZIF-8/PSS layer with angstrom-scale apertures, we enabled selective transport of dehydrated lithium ions (Li+Li+) while blocking larger hydrated ions. This advancement not only improves ion separation efficiency but also establishes a new pathway for designing nanofluidic membranes for sustainable energy applications, particularly in challenging organic solvent environments.


主要貢獻

1. 創新性三連續孔結構膜的設計
我們成功開發了一種新型異質亞納米通道膜（ZIF-8/PSS@BANM），其具有從亞納米到納米再到亞微米的幾何梯度三連續孔結構。這種設計顯著提升了在有機電解質溶液中的離子選擇性、離子整流特性以及超快速離子傳輸能力，克服了傳統膜在有機溶劑中常見的選擇性差和導電性低等限制。

2. 突破性的滲透能量轉換效率
我們的膜在混合2 m LiCl-甲醇與純甲醇溶液時，實現了約50.5 W·m⁻²的前所未有的功率密度，這比現有膜高出45倍以上。這一卓越性能源於ZIF-8/PSS層提供的強整流特性和放大的定向離子傳輸，展示了從有機溶液中高效收集滲透能量的潛力。

3. 離子傳輸機制設計的新突破
通過整合帶負電荷且具有埃級孔徑的ZIF-8/PSS層，我們實現了脫水鋰離子（Li⁺）的選擇性傳輸，同時阻擋較大的水合離子。這一突破不僅提高了離子分離效率，還為設計用於可持續能源應用的納米流體膜開闢了新途徑，特別是在有機溶劑環境中。