Fabrication of Fe3O4@APF Magnetic Nanospheres with Tunable Core-Shell Structure: An Effective Carrier and Reducing Agent for Ag Nanoparticles

In recent decades, magnetic nanomaterials with fast separation and recyclable performance have raised great interest for broad applications in catalysis, protein separation and immunodiagnostics. In this paper, Fe3O4 nanoparticles with a size of (350 +/- 50) nm were produced by the solvothermal method. Then, the nanoparticles were coated with a shell made of 3-aminophenol-formaldehyde (APF) resin to prevent agglomeration. The reaction was very rapid, and core-shell Fe3O4@APF nanospheres were produced by polycondensation within 10 min. Besides, the thickness of the APF shell could be easily adjusted in the range of 10-200 nm by controlling the reaction time and the concentration of 3-aminophenol and formaldehyde. In particular, the APF layer could also act as an effective carrier and reducing agent to capture hundreds of well-dispersed Ag nanoparticles for the abundant hydroxyl groups, obtaining sesame-ball-like Fe3O4@APF@Ag nanocomposites. The structure of sesame-ball can prevent silver nanoparticles from agglomerating, and Fe3O4 core could provide strong magnetism. The magnetic Fe3O4@APF@Ag nanomaterials could catalyze the reduction of organic dyes (4-NP, MB and RhB), and the catalyst possessed high activity, with the conversion of dyes remaining above 90% within 3 min after 7 cycles.

Automated summary

In this study, Fe3O4 nanoparticles were prepared using the solvothermal method, and then coated with a shell made of 3-aminophenol-formaldehyde (APF) resin. Core-shell Fe3O4@APF nanospheres were successfully synthesized within 10 min. The APF shell could also act as an effective carrier and reducing agent to capture dispersed Ag nanoparticles, resulting in the formation of sesame-ball-like Fe3O4@APF@Ag nanocomposites. These magnetic nanomaterials exhibited high catalytic activity for the reduction of organic dyes, with conversion rates remaining above 90% after 7 cycles within 3 min.