Ellagic acid-based iron coordination nanoclusters with delocalized electron transfer for efficient ofloxacin...

Developing environmental functional materials for efficient aquatic antibiotics remediation remains a critical challenge. Herein, an iron-polyphenol coordination nanocluster (Fe-EA NC) consisting of iron and ellagic acid (EA) possessing unique electronic structures was synthesized and applied for effective ofloxacin (OFL) degradation. Notably, the abundant active sites and electron delocalization properties of Fe-EA NC enabled it to efficiently activate peroxydisulfate (PDS) generating diverse reactive oxygen species (ROS) and facilitating the non-radical pathways, achieving 95.9% OFL removal (initial concentration of 25 mg L^-1) within 2 h, at low catalyst dosage of 0.125 g L^-1. Single-factor experiments were conducted to confirm the robust catalytic degradation performance of Fe-EA NC under various environmental conditions with OFL degradation rate remaining over 90% in most cases, including variation of temperature and initial pH, and coexisting interferents. Furthermore, Fe-EA NC exhibited a favorable reusability (over 80% degradation after 5 consecutive cycles). Comprehensive analytics identified the catalytic sites, electron transfer, ROS, and alleviation of overall toxicity to a certain extent. Sufficient theoretical calculations elucidated reaction sites of OFL and catalyst structure-induced electron transfer at the molecular level. This work provides a rational design strategy for high-performance environmental catalytic materials by systematically investigating the molecular characteristics of the EA-based iron coordination complex with prominent electron delocalization properties caused by polyphenolic structure of EA, and the various PDS activation pathways resulting therefrom. Key findings include the formation of multiple efficient catalytic sites via intramolecular charge transfer and electron delocalization, and enhanced OFL electron extraction through intermolecular electron transfer.