Exfoliation of Cu-Containing Poly(triazine imide): From Three-Dimensional to Two-Dimensional Particle Morphology

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Controlling morphology in extended covalent organic frameworks (COFs) is difficult.
• Carbon nitride (CN) materials typically lack long-range order and orientation.
• Achieving crystalline, 2D morphologies in COFs is crucial for advanced applications.

Purpose of the Study:

• To synthesize crystalline carbon nitride (CN) materials with controlled morphology.
• To demonstrate the exfoliation of these CN materials into 2D sheets.
• To develop a novel CN material, poly(triazine imide) copper bromide (PTI-CuBr), and characterize its properties.

Main Methods:

• Synthesis of poly(triazine imide) lithium bromide and poly(triazine imide) copper bromide (PTI-CuBr).
• Flux-assisted cation-exchange process for PTI-CuBr.
• Solvothermal exfoliation of CN materials.
• Characterization using dynamic light scattering, high-angle annular dark-field scanning electron microscopy, energy-dispersive spectroscopy, and X-ray photoelectron spectroscopy.

Main Results:

• Achieved atomically-precise crystalline CN with poly(triazine imide) lithium bromide.
• Developed PTI-CuBr via cation-exchange, retaining internal Cu cations during exfoliation.
• Exfoliated CN into 2D hexagonal sheets (<10 nm thickness, hundreds of nm width).
• Confirmed consistent Cu:Br:N molar ratio and homogeneous PTI pore occupancy post-exfoliation.

Conclusions:

• A novel top-down synthesis approach for 2D CN sheets was developed.
• Maintaining oxygen-free conditions is critical to prevent copper clustering.
• The method provides homogeneous cation occupancy within the CN framework.