Magnetically recyclable ZnO coated Fe3O4 nanocomposite for MO dye degradation under UV-light irradiation

Abstract

We describe the synthesis of zinc oxide (ZnO) coated magnetite (Fe3O4) [ZnO/Fe3O4] nanocomposite and its photocatalytic application towards the methyl orange (MO) dye degradation. ZnO/Fe3O4 nanocomposite was prepared by opting the ex-situ mechanical stirring process of ZnO powder and solvothermally prepared Fe3O4 nanoparticles. The photocatalytic properties of the ZnO/Fe3O4 nanocomposite were investigated, and the degradation of methyl orange (MO) dye was found to be 84% in 120 min under UV light. The electron transfer mechanism might explain the still debatable MO dye degradation mechanism in the present case. The photogenerated electrons transfer to the conduction band (CB) of Fe3O4 from the CB of ZnO under UV light exposure. This results in the creation of defect levels (i.e., Fe2+ or Fe3+) in ZnO, lowering the CB of ZnO. The reusability and efficient magnetic separability of ZnO/Fe3O4 photocatalyst was established by 60% degradation after four cycles under UV light irradiation. The nanocomposite's XRD pattern before and after photocatalytic degradation exhibited no structural change, demonstrating the photocatalyst's outstanding stability. Our investigations demonstrated the potential for MO dye degradation by ZnO/Fe3O4 nanocomposite under UV light irradiation.