Interfacial engineering in Zn/Zr3+-ZrO2-coated AgI nanostructures: step-scheme charge transfer for robust chemical stability and visible-light photocatalysis

Zirconium dioxide (ZrO 2 ) is extensively investigated for the remediation of antibiotic pollution in aquatic environments, owing to its environmental compatibility and favorable electronic structure. However, its ultrawide band gap energy severely restricts visible-light harvesting and visible-light photocatalysis. To overcome these limitations, visible-light-active Zn/Zr 3+ -ZrO 2 and AgI@Zn/Zr 3+ -ZrO 2 nanostructures were synthesized through a calcination-chemical deposition strategy for levofloxacin degradation. The obtained AgI@Zn/Zr 3+ -ZrO 2 composites demonstrated a high specific surface area of approximately 100.65 m 2 g −1 and enhanced visible-light absorption, featuring a red-shifted absorption edge extending to approximately 460 nm. The AgI@Zn/Zr 3+ -ZrO 2 -30% heterojunction exhibited the highest photocatalytic levofloxacin degradation efficiency under visible-light irradiation, achieving a remarkable 80.51% degradation within 18 min. The apparent rate constant was 0.10042 min −1 , which was 5.66 times and 31.28 times of AgI (0.01772 min −1 ) and Zn/Zr 3+ -ZrO 2 (0.00321 min −1 ), respectively. Additionally, the AgI@Zn/Zr 3+ -ZrO 2 composites demonstrated remarkable cycling stability for levofloxacin degradation, retaining 94.67% of the initial performance after three reuse cycles. Crucially, Zr 3+ doping and Step-scheme (S-scheme) heterostructure synergistically enhances interfacial charge dynamics and chemical stability of the AgI@Zn/Zr 3+ -ZrO 2 composites, offering a viable design strategy for high-performance photocatalysis.