Indirect Z-scheme MXene@g-C3N4/MIL-101(Fe) heterojunction for the enhanced visible-light-responsive enrofloxacin photodegradation

Enrofloxacin (ENR), a second-generation fluoroquinolone antibiotic, is a commonly detected antibiotic in aquatic environments, and the search for an efficient elimination strategy is urgently critical. In this work, the visible- light-driven MXene@g-C3N4/MIL-101(Fe) (MX@MCN) nanocomposites were fabricated by thermal solvent method with the well-deposition of g-C3N4/MIL-101(Fe) onto the surface of MXene nanosheets. The MX@MCN nanocomposites exhibit high specific surface area, furnishing numerous reactive sites to expedite photocatalytic degradation of ENR. Moreover, the combination of MXene and MIL-101(Fe)/g-C3N4 increases the sunlight utilization efficiency by narrowing down the bandgap from 2.7 to 2.4 eV. The photon lifetime also increases from 4 to 6 ns because of the indirect Z-scheme heterojunction. The removal efficiency of 10 mg/L ENR over MX@MCN nanocomposites is nearly complete with a superior rate constant of 0.069 min- 1 under neutral conditions. Additionally, the impact of several environmental parameters including catalyst dosage, water matrixes, pH, initial ENR concentration, and co-ions on the photoactivity of MX@MCN was comprehensively elucidated. Results of scavenger experiments conclusively identify that the main contribution of reactive species to ENR photodegradation are the photogenerated hole and O 2 center dot- radicals. These findings highlight the exceptional photocatalytic activity of MX@MCN toward ENR removal, signifying its potential as a foundational platform for constructing indirect Z-scheme g-C3N4/MOF@MXene heterojunctions for water and wastewater treatment applications.