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

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 m and diameters of 0.05 to 0.5 m; 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.