Constructing Z-scheme AgI@MIL-101(Fe) heterojunction photocatalyst for efficient photodegradation of oxytetracycline hydrochloride under visible light

AgI@MIL-101(Fe) photocatalyst was fabricated via in-situ precipitation method. • The photocatalyst achieved 95.25% degradation efficiency of OTC within 180 min. • The photocatalyst exhibited excellent practical applicability in real water samples. • Z-scheme heterojunction mechanism and degradation pathway were elucidated. Owing to their extensive and long-term application as well as poor degradability, antibiotics are inevitably persistent in aquatic environments due to their extensive and long-term use as well as heir difficulty in degradation. The development of efficient photocatalysts is therefore of crucial significance in environmental purification. In this study, a Z-scheme MIL-101(Fe) heterojunction photocatalyst was rationally designed and fabricated via a combined solvothermal and in-situ precipitation methods for the efficient removal of oxytetracycline hydrochloride (OTC), where MIL-101(Fe) is a typical member of the metal-organic framework (MOF) family. A series of characterization methods were employed to systematically observe the morphology and microstructure, optical properties, and photocatalytic performance of the as-prepared photocatalyst. The AgI@MIL-101(Fe) nanocomposites achieved an OTC degradation efficiency of 95.25% within 180 min under visible-light irradiation, demonstrating superior photocatalytic activity compared to a single-component counterparts. Structural characterizations results indicated that AgI formed a tight interface contact with MIL-101(Fe), which provided an effective structural foundation for theheterojunction construction. AgI particles were well dispersed on MIL-101(Fe), effectively mitigating their aggregation and thus creating abundant light absorption and reaction sites for photocatalytic reactions. Photoelectrochemical measurements further demonstrated that the nanocomposite possessed strong light absorption ability and high separation efficiency for photogenerated carriers. The as-prepared photocatalyst also exhibited excellent practical applicability in the treatment of actual water samples from Baiyangdian Lake. Five cycles of experiments indicated that its outstanding structural and catalytic stability. Mechanistic investigations identified superoxide radicals (•O 2 − ) as the primary active factors responsible for OTC degradation. Finally, the typical Z-scheme heterojunction mechanism and degradation pathway of OTC were finally proposed. This work provides a new design strategy and practical reference for the development of high-performance photocatalysts targeting the efficient removal of OTC and other antibiotics from aquatic environments. Download: Download high-res image (211KB) Download: Download full-size image