Introduction of cadmium sulfide quantum dots to construct a dual Z-scheme heterojunction for enhanced photodegradation of norfloxacin

In this study, a novel ternary dual Z-scheme heterojunction photocatalyst (LBQ) was constructed by integrating cadmium sulfide (CdS) quantum dots (QDs) with BiOIO 3 and CoCr-layered double hydroxides (LDHs) for the efficient photodegradation of norfloxacin (NOR) in water. The synergistic effects of CdS QDs and the dual Z-scheme charge transfer pathway endow the system with broadened spectral response, significantly enhanced charge separation, and abundant surface active sites. Under optimized conditions (catalyst dosage, initial NOR concentration, temperature, and pH), the optimal LBQ composite achieved an 87% NOR removal rate within 120 min of visible-light irradiation, with a remarkably low activation energy of 7.289 kJ/mol, indicating a facile and energy-efficient degradation process. Detailed characterizations, including PL, photocurrent, UV–Vis DRS, VB-XPS, and BET analysis, reveal that the internal electric field of the Z-scheme heterojunction effectively promotes photogenerated electron–hole pair separation, while the introduction of CdS QDs further creates an additional Z-scheme electron transfer channel and enhances light absorption and specific surface area via quantum confinement effects. This work provides a new strategy for designing high-performance photocatalysts for antibiotic wastewater treatment. Download: Download high-res image (154KB) Download: Download full-size image