Synthesizing Interpenetrated Triazine-based Covalent Organic Frameworks from CO₂.

Area of Science:

• Materials Science
• Green Chemistry
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) are nitrogen-rich porous materials with high stability.
• Traditional COF synthesis often involves harsh conditions and results in low crystallinity.
• COFs show potential in various energy applications.

Purpose of the Study:

• To develop an environmentally friendly synthesis route for crystalline COFs.
• To utilize carbon dioxide (CO2) as a precursor for COF synthesis.
• To investigate the properties and potential applications of CO2-derived COFs.

Main Methods:

• Two-step synthesis involving CO2 and piperazine to form 1,4-piperazinedicarboxaldehyde.
• Condensation of the intermediate with melamine to construct the COF framework.
• Characterization using powder X-ray diffraction, HRTEM, and SAED.

Main Results:

• Achieved a 46.3% mass ratio of CO2 conversion into the COF formula unit.
• The CO2-derived COF exhibits a 3-fold interpenetrated structure with a high surface area (945 m²/g).
• Demonstrated high stability against strong acids, bases, and boiling water.
• Post-modification enabled modulation of hydrophilicity and achieved a proton conductivity of 2.5×10⁻² S/cm.

Conclusions:

• A sustainable and efficient method for synthesizing crystalline COFs from CO2 has been established.
• The resulting COFs possess desirable structural and stability characteristics for energy applications.
• The CO2-derived COFs show promise for applications requiring proton conductivity.