Fe3O4-Ag heterostructure nanocrystals with tunable Ag domains and magnetic properties

Fe3O4-Ag dimers and multimers with tunable Ag domains and magnetic properties were prepared by a seeding growth method. The reaction mechanism based on the attraction between Ag precursor and Fe3O4 particles as well as the migration of adsorbed Ag species towards the initially deposited Ag domain was proposed to explain the heterogeneous nucleation of Ag on Fe3O4 and the tuning of Ag crystal numbers. Ligand oleic acid, low reaction temperature, large seeding particle and nonpolar solvent are found to be favourable to the growth of Fe3O4-Ag HNCs with more discrete Ag domains. The Fe3O4-Ag HNCs show composition and structure related magnetization behaviour and MR contrast effect, which can be developed into a dual function material for bio-therapy when utilizing the plasmonic, fluorescent or antibacterial properties of Ag at the same time.