Recyclable Fe3O4/Au Nanocomposites for Oxidation Degradation of Methylene Blue in Near Neutral Solution

Abstract

Fe3O4/Au nanocomopsites (Fe3O4/Au NPs) with much improved catalytic activity were successfully fabricated through a simple seed growth method in aqueous solution. The petal-like structure, high saturation magnetization, the negatively charged sodium citrate-stabilized Fe3O4/Au NPs was characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), dynamic light scattering (DLS) and vibrating sample magnetometry (VSM). The activated-H2O2 ability of Fe3O4/Au NPs was evaluated by using methylene blue (MB) as a cationic phenothiazines dye to be degraded in near neutral solution. The results showed Fe3O4/Au NPs removed over 95% MB from an aqueous solution within 60[Formula: see text]min under the optimum conditions. The apparent rate constant of Fe3O4/Au NPs was [Formula: see text][Formula: see text]min[Formula: see text] which was 43.2 and 8.3 times higher than pure Fe3O4 ([Formula: see text][Formula: see text]min[Formula: see text] and Au ([Formula: see text][Formula: see text]min[Formula: see text] NPs. The enhanced catalytic activity and increased oxidation rate constant probably owing to the synergistic effect between Fe3O4 and Au NPs to activate H2O2 generate a large amount of strong oxidizing species, such as [Formula: see text]. In addition, nanocrystalline structure of Fe3O4/Au NPs was also very important to the peroxidase-like effect, especially the interaction interface between Fe3O4 and Au NPs. Moreover, Fe3O4/Au NPs was stable and could be regenerated and reused for at least five cycles.