Interface-engineered N-CQD/g-C₃N₄ Heterostructures with tunable opto-elctronic features and enhanced thermal conductivity

Document Type

Article

Publication Date

3-1-2026

Abstract

The heterostructures of nitrogen doped carbon quantum dots (N-CQDs) with graphitic carbon nitride (g-C3N4) were fabricated using hydrothermal approach. Physicochemical characterizations, including FTIR, XRD, XPS, and HR-TEM were used to explore the phase structure, chemical composition and morphological structure of the heterostructures. The optical characteristics were investigated via using UV–vis spectrophotometry. The results confirm the strong coupling and compounding between N-CQDs and g-C3N4 to form a 0D/2D heterojunction. Furthermore, using the Tauc equation, the optical bandgap energy for g-C3N4 was dropped from 2.805 eV after conjugation with N-CQDs, reaching 2.797 eV, 2.76, and 2.795 as the concentration of N-CQDs in the heterostructure increased. Meanwhile, the PL of heterostructures is gradually blue shifted. However, upon increasing the amount of N-CQDs in the heterostructure, the extinction coefficient, refractive index, electronegativity, and optical conductivity enhanced. It is shown that Skin depth (δ) decreases as photon energy increases up to cut off wavelength λcutoff ∼ 3.8 eV, then increases exponentially with N-CQDs content in surface g-C3N4 sheets. Photoacoustic spectroscopy technique (PA) was used to evaluate the thermal diffusivity (α), thermal effusivity (e) and thermal conductivity (k) of prepared materials. The results show the values of (k) of g-C3N4 reached to 300 % increase upon conjugation with N-CQDs. Additionally, the thermal conductivity increased from 0.126 w m−1k−1to 0.596 w m−1 k−1, and the e values increased from 40 to 63.4 ws1/2m−2k−1 as the concentration of N-CQDs increase in the heterostructures. Finally, these results demonstrate the potential of N-CQDs/g-C₃N₄ heterostructures for multifunctional optoelectronic and thermal applications.

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