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Updated: Jun 16, 2026
07:45
Electrophoretic Crystallization of Ultrathin High-performance Metal-organic Framework Membranes
Published on: August 16, 2018
Asymmetric Pore Engineering in Covalent Organic Framework Membrane for Effective Osmotic Energy Conversion
Ki Ryuk Bang1, Choah Kwon2, Ye Ji Shin1
1Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
ACS Nano
|June 15, 2026
Summary
Researchers developed an asymmetric covalent organic framework (COF) membrane that significantly boosts energy generation from salinity gradients. This innovative membrane design enhances ionic conductivity and power output for reverse electrodialysis (RED) applications.
Area of Science:
- Materials Science
- Electrochemistry
- Chemical Engineering
Background:
- Reverse electrodialysis (RED) utilizes salinity gradients for electrical energy generation.
- Covalent organic frameworks (COFs) offer promising membrane materials with tunable properties.
- Imine-based COFs provide high ion selectivity but suffer from limited ionic conductivity due to hydrophobic channels.
Purpose of the Study:
- To engineer an imine-based COF membrane with asymmetric channel structures to enhance RED performance.
- To modulate ion transport by creating a gradient in pore chemistry along the membrane's diffusion path.
Main Methods:
- Fabrication of imine-based COF membranes.
- Asymmetric surface treatment using an alkaline solution to partially hydrolyze imine bonds and introduce hydrophilicity.
- Characterization of membrane structure, ion transport properties, and RED performance.
Main Results:
- The alkaline treatment created asymmetric channels, enhancing hydrophilicity on one side while maintaining the crystalline framework on the other.
- The optimized asymmetric COF membrane achieved a power density of 6.07 W/m², a 14.8-fold increase compared to the pristine COF.
- The modified membrane demonstrated an improved balance between ionic conductivity and selectivity.
Conclusions:
- Localized chemical modification of nanochannel environments is an effective strategy for designing advanced membranes.
- Asymmetric COF membranes offer a tunable approach to optimize ion transport for enhanced energy conversion.
- This work provides a versatile platform for developing high-performance membranes for RED and other separation applications.
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