Sulfur-vacancy-enriched ZnIn₂S₄ rods for accelerated photocatalytic degradation of antibiotics via enhanced oxygen activation and charge dynamics

The removal of persistent antibiotics from wastewater is a critical challenge for sustainable environmental remediation. Photocatalysis offers a promising solution, yet its efficacy is often limited by inefficient structural design and inadequate activation of molecular oxygen (O₂). Here, we report a rod-shaped ZnIn₂S₄ photocatalyst enriched with strategically engineered sulfur vacancies (Sv-ZIS) that address these bottlenecks. The introduction of sulfur vacancies narrows the bandgap, enhancing visible-light absorption and inducing defect levels that facilitate superior charge separation and transfer. These vacancies also boost the adsorption energy and chemisorption of O₂ molecules, thereby catalyzing the production of superoxide radicals (˙O₂⁻) with high efficiency. The rod-like morphology further augments the adsorption and interaction of tetracycline molecules with reactive oxygen species (ROS), significantly enhancing photocatalytic degradation performance. Sv-ZIS achieves tetracycline degradation rates nearly fourfold greater than its bulk counterpart (Bulk-ZnIn₂S₄), underscoring its transformative potential. This work pioneers a novel structural and defect engineering strategy, advancing the development of high-performance photocatalysts for tackling antibiotic pollutants in wastewater treatment.