Construction of ZnFe 2 O 4 /rGO composites as selective magnetically recyclable photocatalysts under visible light irradiation

Abstract This paper reports on highly active ZnFe 2 O 4 /reduced graphene oxide (ZnFe 2 O 4 /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 ZnFe 2 O 4 nanoparticles (NPs) with a diameter of 15 ∼ 50 nm were densely grown on the rGO substrates. The photocatalytic activities of ZnFe 2 O 4 /rGO catalysts were evaluated by the degradation of Methylene blue (MB) under visible light. The results showed that the ZnFe 2 O 4 /rGO catalysts had high photocatalytic activity, and the degradation efficiency of MB was almost 100% within 180 min. Moreover, the ZnFe 2 O 4 /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 ZnFe 2 O 4 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 H 2 O 2 on ZnFe 2 O 4 /rGO catalysts, which was responsible for the oxidation of the dyes. Of note, the ZnFe 2 O 4 /rGO catalyst maintained an efficiency of over 90% after five cycles. The XRD, XPS and VSM characterization revealed that the ZnFe 2 O 4 /rGO catalysts had a stable crystal structure and can be easily separated.