Boosting photocatalytic efficiency and nonlinear optical response of graphitic carbon nitride by infusing carbon nanotubes

• Published in: Journal of molecular structure 2025-02, Vol.1321, p.140089, Article 140089
• Main Authors: Johnson, Elza, Reji, Nirmal, A, Anjitha, K, Shijina, Sridharan, Kishore
• Format: Article
• Language: English
• Subjects: Bisphenol A; Carbon nanotube; Graphitic carbon nitride; Nonlinear absorption; Visible light active photocatalyst
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2024.140089

•Developed g-C3N4/CNT composites via one-pot solid-state pyrolysis technique.•Bandgap of g-C3N4 reduced from 2.6 eV to 2.35 eV with minimal CNT addition.•Achieved a 12-fold increase in two-photon absorption with 0.5 wt% CNT infusion.•Enhanced BPA degradation, photocatalytic efficiency 10 times higher than g-C3N4.•CNTs improve charge separation, boosting both optical and catalytic performance. Nanostructured materials are widely studied for their light-driven physical and chemical processes, which are key to their potential in photophysical applications. We introduce a one-pot solid-state pyrolysis technique for the synthesis of graphitic carbon nitride/carbon nanotube (g-C3N4/CNT) composites. The formation of the composite was characterized through X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy. Notably, UV-vis diffuse reflectance spectroscopy indicated a reduction in the bandgap of pure g-C3N4 from 2.6 eV to 2.35 eV with the incorporation of 0.5 wt% CNT. The nonlinear optical transmission of the samples was analyzed at 532 nm using the open-aperture Z-scan technique employing 5 ns laser pulses, revealing a twelve-fold increase in the two-photon absorption coefficient (b) for g-C3N4/CNT0.5 compared to pristine g-C3N4. Remarkably, g-C3N4/CNT0.5 showed enhanced photocatalytic efficiency in degrading bisphenol A (BPA), with the kinetic constant (k) being ten times higher than that of pure g-C3N4. The improved photocatalytic performance of g-C3N4/CNT0.5 is attributed to the presence of CNTs, which act as effective electron acceptors and transfer channels, significantly enhancing the separation of photogenerated charge carriers in g-C3N4, as evidenced by the decreased intensity in the photoluminescence spectrum.