3D covalent organic framework membrane with fast and selective ion transport

Area of Science:

• Materials Science
• Electrochemistry
• Separation Science

Background:

• Ionic covalent organic framework (COF) membranes offer potential to overcome the trade-off between ion conductivity and selectivity.
• Exploitation of 3D COF membranes for enhanced ion transport remains an underexplored area.

Purpose of the Study:

• To fabricate and characterize a 3D sulfonic acid-functionalized COF membrane (3D SCOF) for efficient and selective ion transport.
• To evaluate the performance of the 3D SCOF membrane in osmotic energy conversion.

Main Methods:

• Fabrication of 3D SCOF membranes via a dual acid-mediated interfacial polymerization strategy.
• Characterization of membrane properties including pore size, ion exchange capacity, and proton conductivity.
• Testing the membrane's performance in osmotic energy conversion.

Main Results:

• The 3D SCOF membranes exhibit interconnected ion transport channels, ultramicroporous sizes (0.97 nm), and high sulfonate group density (4.1 mmol g⁻¹).
• Achieved high proton conductivity of 843 mS cm⁻¹ at 90 °C.
• Demonstrated high power density (21.2 W m⁻²), selectivity (0.976), and energy conversion efficiency (45.3%) in osmotic energy conversion.

Conclusions:

• The developed 3D SCOF membranes provide an effective platform for simultaneous high ion conductivity and selectivity.
• This work presents a novel approach for 3D ionic COF membranes, advancing their application in ion transport and separation technologies.