Photo-Fenton degradation of tetracyclines over cascade dual Z-scheme g-C3N4/MoS2/ZnFe2O4 heterojunction: Degradation pathways, mechanistic insights and fluorescence recognition

Considering adverse impact of the presence of ubiquitous antibiotics in natural water systems, the research focus has been deviated towards development of environment-friendly multifunctional materials. Herein, a novel direct dual Z-scheme g-C3N4/MoS2/ZnFe2O4 (CNMoZnFe) heterojunction composites (with varied weight ratios) were prepared via sonication-calcination methodology. FE-SEM and HR-TEM studies revealed the proper dispersion of ZnFe2O4 nanoparticles over 2D nanosheets of CN and MoS2, depicting the close interfacial contact between all the individual components present in ternary heterostructure. Highly efficient photocatalytic degradation of tetracyclines (TCs) antibiotics; namely tetracycline (TC) and minocycline (MC) was perceived with rate kinetics values of TCs removal over CNMoZnFe-5 to be approximately 5, 9 and 8 times higher than pristine CN, MoS2 and ZnFe2O4, respectively. The outstanding photocatalytic performance of fabricated heterostructure could be due to the synergistic effect of Z-scheme charge carrier separation alongwith photo-Fenton mechanism. The CNMoZnFe-5 heterostructure's 80 % TC mineralisation ability underscored the material's TC removal efficiency. LC-MS revealed photocatalytic degradation mechanisms. Recyclability and phytotoxicity tests verify magnetically retrievable composites' viability. The smart ternary heterostructure proved highly selective for fluorescence sensing of TCs, with detection limits of 3.5 mu M for TC and 3.2 mu M for MC.