Construction of ZnFeO/rGO composites as selective magnetically recyclable photocatalysts under visible light irradiation.

This paper reports on highly active ZnFeO/reduced graphene oxide (ZnFeO/rGO) nanocomposites synthesized by a modified sol-gel method. The as-prepared samples have been characterized by XRD, TEM, XPS and other detection methods, which demonstrate that ZnFeO nanoparticles (NPs) with a diameter of 15 ∼ 50 nm were densely grown on the rGO substrates. The photocatalytic activities of ZnFeO/rGO catalysts were evaluated by the degradation of Methylene blue (MB) under visible light. The results showed that the ZnFeO/rGO catalysts had high photocatalytic activity, and the degradation efficiency of MB was almost 100% within 180 min. Moreover, the ZnFeO/rGO catalysts also had a great removal effect on Rhodamine B (RhB) and Methyl orange (MO). Mechanistic studies revealed that the rGO acted as a stabilizer to prevent ZnFeO from aggregation and improved the separation of photo-generated electrons. The high efficiency for dye degradation was attributed to the generation of hydroxyl radicals (·OH) via the photochemical decomposition of HO on ZnFeO/rGO catalysts, which was responsible for the oxidation of the dyes. Of note, the ZnFeO/rGO catalyst maintained an efficiency of over 90% after five cycles. The XRD, XPS and VSM characterization revealed that the ZnFeO/rGO catalysts had a stable crystal structure and can be easily separated.