In-situ silver-bridged interfaces drive Z-scheme coupling on iron-doped NH₂-UiO-66(Zr)/silver iodide for efficient...

Fluoroquinolone antibiotics like ciprofloxacin (CIP) pose environmental risks when released into water. Herein, a visible-light-active Fe-doped NH₂-UiO-66(Zr)@AgI Z-scheme heterostructure was prepared via an ion exchange precipitation method. By varying AgI content, reduced particle size and enhanced charge separation for efficient photodegradation was achieved. The optimum composition (Fe-UNH@AgI-20) exhibited a 95.2 % degradation efficiency toward CIP after 60 min of visible-light irradiation. It also showed high removal efficiencies for tetracycline, lomefloxacin, and Rhodamine B. Reaction kinetics followed pseudo-first-order behavior, with rate constants significantly higher than those of pristine NH₂-UiO-66(Zr) and AgI. The catalyst maintained 85.1 % activity after cycles, indicating good stability. Scavenger tests and electron paramagnetic resonance (EPR) analyses identified holes (h⁺), superoxide radical (•O₂^-), and hydroxyl radical (•OH) as key reactive species. Fe doping enhanced visible-light absorption and created defect sites, while AgI introduction promoted charge separation and suppressed AgI photocorrosion. Under irradiation, a small fraction of Ag⁺ was reduced to metallic Ag, forming an electron bridge that switched the initial type-II heterojunction to a Z-scheme configuration. This Z-scheme mechanism efficiently separated carriers, facilitated generation of ROS, and enabled thorough mineralization of CIP; toxicity predictions showed most products were less mutagenic than CIP, confirming reduced ecological risk. The findings demonstrate that the Fe-doped NH₂-UiO-66(Zr)@AgI heterostructure is a promising photocatalyst for antibiotic-contaminated wastewater remediation.