Temperature-Triggered Structural Boundary between Nitrogen-Doped Carbon Dots and Graphene Quantum Dots

Area of Science:

• Materials Science
• Nanotechnology
• Carbon Nanomaterials

Background:

• Nitrogen-doped carbon dots (N-CDs) and nitrogen-doped graphene quantum dots (N-GQDs) are similar carbon nanostructures.
• Distinguishing between N-CDs and N-GQDs is challenging due to synthesis variations.

Purpose of the Study:

• To elucidate the structural boundary between N-CDs and N-GQDs.
• To establish a clear classification based on correlated properties.

Main Methods:

• Synthesis of N-CDs and N-GQDs via identical solvothermal route, varying only reaction temperature.
• Characterization using electron microscopy, selected-area electron diffraction, optical absorption, photoluminescence, and dielectric measurements.

Main Results:

• N-CDs exhibit amorphous carbon frameworks.
• N-GQDs show nanocrystalline graphene domains with distinct lattice fringes and diffraction rings.
• N-GQDs possess enhanced sp2 conjugation, evidenced by optical properties.
• N-CDs display stronger dielectric dispersion due to interfacial and defect polarization.

Conclusions:

• A common chemical pathway yields distinct structural outcomes for N-CDs and N-GQDs.
• Classification can be based on correlated structural, optical, and dielectric signatures.
• This work clarifies the differentiation between these related carbon nanomaterials.