Fine-tuning photoluminescence and photocatalysis: Exploring the effects of carbon quantum dots synthesis and purification on g-C3N4

This study investigates the constituents of microwave-synthesized carbon quantum dots (CQDs) and their effects on the photocatalytic performance of graphitic carbon nitride (g-C3N4) semiconductors. The synthesized g-C3N4 and CQDs were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-visible (UV-vis) spectroscopy, and Raman spectroscopy. The influence of CQD synthesis parameters on photoluminescence (PL) behavior was analyzed through time-integrated photoluminescence spectroscopy and time-resolved photoluminescence spectroscopy (TRPL). CQD purification via column chromatography and heat treatment enhanced the photocatalytic efficiency of CQDs/g-C3N4 composites, achieving up to 90 % methylene blue (MB) degradation. Extended CQDs pyrolysis resulted in fluorophore degradation and the formation of carbogenic cores, contributing to increased photocatalytic activity. Cytotoxicity testing confirmed the nontoxic nature of CQDs components and the composite. The high efficiency, low toxicity, and durability of the CQDs/g-C3N4 photocatalyst present promising applications for renewable energy, environmental remediation, and sustainable chemical processes.