Reversible Exfoliation-Aggregation Dynamics in Ionic COFs for Tunable Interfacial Catalysis

Area of Science:

• Materials Science
• Nanotechnology
• Catalysis

Background:

• 2D covalent organic frameworks (COFs) are vital for catalysis, adsorption, sensing, and energy storage.
• Their performance is limited by static interfacial behavior, lacking dynamic structural models.

Purpose of the Study:

• To design and synthesize a novel ionic COF (iCOF) with reversible dynamic behavior in aqueous media.
• To enable bidirectional control over particle size and phase states for enhanced functionality.

Main Methods:

• Precise tuning of the iCOF skeleton and counterions to achieve dynamic exfoliation and aggregation.
• Photocatalytic hydrogen evolution (PHE) studies to correlate performance with concentration and particle size.
• Mechanistic analysis using weak-force interactions and soft-hard acid-base theory.

Main Results:

• The synthesized iCOF, I-4, exhibits reversible exfoliation and aggregation in water.
• A strong correlation was found between solution concentration, particle size, and PHE efficiency.
• I-4 achieved a PHE rate of 190 mmol g^-1 h^-1 at 35°C and demonstrated efficient recovery via iodide salt addition.

Conclusions:

• The dynamic nature of iCOF I-4 allows for tunable interfacial adaptability.
• This reversibility is driven by synergistic effects of counterion assembly and framework structure.
• The findings open avenues for next-generation dynamic COFs in catalysis, ion transport, and separation.