A novel 2D/1D core-shell heterostructures coupling MOF-derived iron oxides with ZnIn₂S₄ for enhanced photocatalytic...

1D spindle-like iron oxides with controllable phase were synthesized by using MIL-88A-templated pyrolysis under different atmospheres, thermal annealing in N₂ to obtain Fe₃O₄ and in air to obtain α-Fe₂O₃. Then, 2D/1D core-shell heterostructures (ZnIn₂S₄@Fe₃O₄ and ZnIn₂S₄@α-Fe₂O₃) were constructed by in-situ self-assembly strategy. Characterizations indicated that the 2D ultra-thin ZnIn₂S₄ shell with 0.3 μm was homogeneously coated on the surface of 1D Fe₃O₄/α-Fe₂O₃ core with 1 μm, and ZnIn₂S₄@Fe₃O₄ exhibited higher BET surface area (84.5 m² g^-1) compared with ZnIn₂S₄@α-Fe₂O₃ (17.8 m² g^-1), providing more exposed active sites and larger contact area. The ZnIn₂S₄@Fe₃O₄-5 showed the best photocatalytic activity of RhB degradation as compared to ZnIn₂S₄, Fe₃O₄ and ZnIn₂S₄@α-Fe₂O₃. In addition, the degradation rates of MB, BPA and MO over ZnIn₂S₄@Fe₃O₄ were much higher than that of ZnIn₂S₄@α-Fe₂O₃. The proposed photocatalytic mechanism was also discussed: the Fe₃O₄ as an electron acceptor caused Fe³⁺/Fe²⁺ cycle in ZnIn₂S₄@Fe₃O₄ and ZnIn₂S₄@α-Fe₂O₃ followed the Z-scheme mechanism.