Spatially engineered of ionic chains in one-dimensional covalent organic frameworks for efficient uranium...

Area of Science:

• Materials Science
• Environmental Chemistry
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) show promise for U(VI) reduction but suffer from hydrophobicity and poor charge mobility.
• Existing ionic modification methods can disrupt COF structure and reduce efficiency.

Purpose of the Study:

• To develop a spatial site-engineering strategy for precise ionic chain placement in COFs.
• To enhance the photocatalytic performance of COFs for U(VI) reduction.

Main Methods:

• Controlled orientation of nitrogen sites in V-shaped phenanthroline monomers to position ionic chains.
• Synthesis of one-dimensional COFs with ionic chains inside channels, outside channels, or both.
• Characterization of structural integrity, charge dynamics, and hydrophilicity.

Main Results:

• Optimized zwitterionic COF (COF-IO-SO3-) demonstrated excellent U(VI) reduction (1806.87 mg g-1).
• Achieved over 95% U(VI) removal from real uranium-mining wastewater.
• Enhanced hydrophilicity, preserved crystallinity, and strengthened built-in electric field.

Conclusions:

• Spatially controlled ion functionalization is a viable molecular design principle for COF photocatalysts.
• The strategy improves U(VI) reduction efficiency and stability in aqueous conditions.
• This approach advances COF applications in environmental remediation, particularly for uranium removal.