Fe3O4/ZnFe2O4 micro/nanostructures and their heterogeneous efficient Fenton-like visible-light photocatalysis process

Abstract

Micro/nanostructured Fe₃O₄/ZnFe₂O₄ composites (MNFZs) were synthesized by a one-step hydro-thermal method. The sample exhibited an urchin-like hierarchical micro/nanostructure composed of nanorods with lengths of 0.2 to 1.5 μm and diameters of 0.05 to 0.5 μm; these have been characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). By decomposing R6G under visible-light irradiation in a heterogeneous Fenton-like photocatalysis reaction, the degradation efficiencies of MNFZs were much higher than those of micro-sized Fe₃O₄, nano-sized Fe₃O₄ and pure ZnFe₂O₄. The highly efficient photocatalysis of the MNFZs was ascribed to their pore structure and the synergistic effect of Fe₃O₄ and ZnFe₂O₄. This unique structure was found to be able to control the release of hydroxyl radicals (˙OH) and improve their utilization rate. The MNFZs retained good photocatalysis properties even after being recycled 6 times. According to chemical oxygen demand (COD) studies, the mineralization ratio of R6G was 71.35% after 80 min, implying that R6G is mineralized in this photocatalysis process. In addition, the MNFZs are stable and can be easily separated by a magnetic separation process; also, their fabrication process can be readily scaled up.