Construction of 3D flower-like Bi5O7I/Bi/Bi2WO6 heterostructure decorated NiFe2O4 nanoparticles for photocatalytic destruction of Levofloxacin in aqueous solution: Synergistic effect between S-scheme and SPR action

Promoting the separation activity of photo-induced carriers via the design of heterostructure photocatalysts remains a vital challenge. In the present study, multistep strategies were developed to construct the Bi5O7I/Bi/ Bi2WO6/NiFe2O4 heterojunction by in situ growth of Bi/Bi2WO6 and NiFe2O4 species on the surface of Bi5O7I microspheres, forming a 3D flower-like structure as verified by characterization technologies. The developed heterojunction reflected superior photodegradation activity (97.5% in 90 min) toward levofloxacin (LEV) under visible light irradiation. The enhanced photodegradation activity of the Bi5O7I/Bi/Bi2WO6/NiFe2O4 nano-composite could be attributed to the synergistic outcomes of the S-scheme mechanism and the plasmonic action of Bi metal in one system. Furthermore, the Bi metal can directly harvest the simulated sunlight under the surface plasmon resonance (SPR) action, which contributes to generating a large number of electron-hole pairs. Some influencing factors like pH, LEV concentration, and catalyst loading were also discussed. The photocatalytic degradation pathways of LEV were investigated depending on the detected intermediate products. The radical experiment and ESR results stated that the major contribution of (OH)-O-center dot, O-center dot(2)-, and h(+) radicals in LEV destruction. The recyclability experiments indicated the excellent stability and facile reusability of the magnetic Bi5O7I/Bi/ Bi2WO6/NiFe2O4 composite. Finally, the photocatalytic mechanism for LEV destruction was clarified in terms of trapping experiments and band-gap discussions. This work introduces a clear technology to fabricate a quater-nary S-scheme heterojunction boosted by the plasmonic effect of Bi metal to accelerate the charge separation ability and create a powerful redox potential to achieve a desirable LEV treatment process.