Synthesis of carbon quantum dots decorating Bi₂MoO₆ microspherical heterostructure and its efficient photocatalytic degradation of antibiotic norfloxacin

In this study, three-dimensional microspherical CQDs/Bi₂MoO₆ heterostructures were synthesized using a simple alcohol-thermal method. It was found that the CQDs/Bi₂MoO₆ had a large specific surface area of 56.0 m²/g, and the introduction of CQDs extended the light absorption spectrum from 480 nm to 496 nm. When utilizing the synthesized CQDs/Bi₂MoO₆ composite for photocatalytic degradation of antibiotic norfloxacin in a water environment, complete decay of norfloxacin and effective removal of total organic carbon (TOC) were achieved within 30 min. Through the optimization of material synthesis and experimental conditions, the optimal CQDs loading amount was determined as 200 μL, the optimal CQDs/Bi₂MoO₆ dosage was 0.8 g/L. Moreover, the CQDs/Bi₂MoO₆ worked well under a wide pH range of 4.4–10.8. The coexistence of HCO_3⁻ enhanced the norfloxacin decay, while the presence of Cl⁻, NO_3⁻ , and SO₄ ²⁻ slightly retarded it. The synthesized CQDs/Bi₂MoO₆ had the great potential in removing and mineralizing norfloxacin in real aquatic environments.