Monoclinic ZrO2 nanospheres supported nitrogen-enriched carbon nitride nanosheets for efficient photodegradation of ciprofloxacin

Antibiotics in water are a major pollutant that poses serious threats to ecosystems and human health, underscoring the urgent need for effective purification methods. Photocatalysis with semiconducting nanomaterials stands out as one of the most efficient and environmentally friendly advanced oxidation processes (AOPs) for degrading harmful organic pollutants. Nitrogen-enriched graphitic carbon nitride (g-C₃N₅), a versatile 2D nanomaterial, is recognized for its visible light-active properties, with several advantages for photocatalytic applications. However, its efficacy is often hindered by high charge recombination rates. Herein, wide bandgap nano zirconia was employed as a robust cocatalyst to enhance the photocatalytic performance of g-C₃N₅. The ZrO₂/g-C₃N₅ (ZC) composites were formed at different weight ratios (1:2, 1:1, 2:1) using a simple ultrasonication method. The successful formation of the composite was confirmed through various analyses, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), photoluminescence (PL), and ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS). Notably, the 1:1 ZC composite achieved an impressive 94.2% degradation of ciprofloxacin under solar light for 90 min at pH 5, attributed to the synergistic interaction between the two catalysts. The composite facilitates a type II heterojunction, with superoxides and holes serving as key radicals in the degradation pathway, and the degradation rates followed pseudo-first-order kinetics. Moreover, the catalyst demonstrated remarkable stability over four cycles, confirmed by reusability tests and post-degradation analyses, which showed minimal changes in structure or morphology. This proposed composite represents a significant advancement in visible light-mediated ciprofloxacin degradation. By incorporating insulating nano zirconia into the g-C₃N₅ matrix, photocatalytic efficacy was restrained. This approach effectively suppresses charge recombination, and promotes enhanced charge transport, paving the way for more efficient photocatalytic applications.

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