Carbon Dots-Mediated Z-Scheme Heterojunction of UiO-66-NH ₂ /BiOCl for Enhanced Visible-Light-Driven Degradation of Antibiotics and Dyes

The ubiquitous accumulation of antibiotics and synthetic dyes in aquatic environments has emerged as a critical threat to the ecological integrity and human health. Visible-light-driven photocatalysis represents a sustainable strategy for decontaminating such pollutants; yet, its practical efficacy is often hampered by narrow light-harvesting ranges and rapid photogenerated carrier recombination. Herein, a ternary photocatalyst, namely, CDs/UiO-66-NH₂/BiOCl (CUCl), was rationally constructed by integrating carbon dots (CDs) into a UiO-66-NH₂/BiOCl Z-scheme heterojunction. Serving as an efficient electron reservoir, the introduced CDs not only significantly extended the visible-light absorption range but also effectively suppressed carrier recombination. Under visible-light irradiation, the optimized CUCl catalyst achieved remarkable degradation efficiencies of 87.2% and 98.8% for tetracycline and rhodamine B, respectively, outperforming the binary UiO-66-NH₂/BiOCl heterojunction and pristine BiOCl. Radical trapping experiments and photocatalytic mechanism investigations revealed that photogenerated holes (h⁺) and superoxide radicals (·O₂^-) were the dominant active species responsible for pollutant degradation. Moreover, the CUCl catalyst exhibited excellent structural stability and reusability, retaining more than 85% of its initial catalytic activity after four consecutive reuse cycles. This work provides a novel and viable strategy for fabricating high-efficiency, stable environmental photocatalysts via the synergistic integration of Z-scheme heterojunctions and carbon dot functionalization.