A novel method for the preparation of conductive and magnetic Fe₃O₄@ag hybrid nanoparticles

A facile and novel strategy was successfully explored for the synthesis of Ag-deposited polydopamine (PDA)-coated Fe₃O₄ magnetic nanoparticles, which shows its advantages of nontoxic, controllable, simple, and inexpensive. Firstly, the surfaces of the particles were functionalized by polydopamine (PDA), and then silver was plated on the Fe₃O₄-PDA surfaces by electroless plating. The surface morphologies of the nanoparticles were observed by high-resolution transmission electron microscopy (HRTEM) and transmission electron microscopy (TEM). The thermal stability of the particles was studied by Thermo Gravimetric Analyzer (TGA). The chemical compositions and the structures of the nanoparticles were characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. In addition, the electrical and magnetic properties were investigated by four-probe electrical conductivity tester and vibrating sample magnetometer (VSM), respectively. The results of XPS and HRTEM indicated that PDA, with a controllable thickness by adjusting the reaction conditions, successfully polymerized on the surfaces of Fe₃O₄ nanoparticles without affecting their crystal structures, and other results demonstrated the perfect deposition of silver nanoparticles. The composite Fe₃O₄-PDA@Ag nanoparticles show good conductivity of 2.50×10⁴ S/cm and large saturation magnetization of 32.6 emu/g.