Preparation, Characterization And Applications Of Silver Doped Magnetic Nanoparticles

Fe3O4magnetic nanoparticles have many unique properties, such as superparamagnetic, small size effects, macroscopic quantum tunneling effects, and so on. Due to these unique properties, Fe3O4magnetic nanoparticles have great potential for various applications, such as magnetic recording materials, magnetic fluid materials, dyes, catalysis and electronic materials, especially have potential applications in biomedical field. Ag nanoparticles show excellent properties in catalysis, optics, and antibacterial because of their nanometer size, high surface activity and energy. By incorporating the magnetic nanoparticles and Ag nanoparticles, the formed Ag doped Fe3O4magnetic nanoparticles possess excellent properties of both Fe3O4and Ag nanoparticles and exhibit potential applications in various fields. In this paper, two novel Ag doped Fe3O4core-shell magnetic nanocomposites have been prepared, and their properties and applications have also been studied.This dissertation consists of four chapters:Chapter1:This part generally introduced the properties, preparation, applications, and research status of Fe3O4nanoparticles, Ag nanoparticles, and Ag doped Fe3O4magnetic nanocomposites.Chapter2:A simple electroless plating method has been used to deposite Ag nanoparticles on the surface of Fe3O4@SiO2magnetic nanoparticles. The architecture was characterized by powder X-ray diffraction (XRD), Transmission electron microscopy (TEM), High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM), which confirmed the formation of Fe3O4@SiO2-Ag nanocomposites. Fe3O4@SiO2-Ag nanocomposites have a core-shell nanostructure, which can be used as a catalyst for the decolorization of dyes in wastewater. The reaction temperature, dosage, and existence of surfactants all affected the reaction rate.Chapter3:Ag@Fe3O4core-shell nanospheres were synthesized by a facile one-pot solvothermal approach. XRD, XPS, TEM, EDX-mapping, and VSM were used to characterize the nanospheres. The Ag@Fe3O4nanospheres can serve as an efficient SERS substrate, which can be prepared by the self-assembling of the magnetic nanoparticles with the help of a magnet. The typtical analytes rhodamine6G and4-aminothiophenol were selected as the model to validate the efficiency of this substrate, and the results indicated that this substrate is stable, reproducible, and especially recyclable.Chapter4:Fe3O4@SiO2-Ag nanoparticles substrate was prepared and their SERS activity was illustrated by rhodamine6G (R6G) and crystal violet (CV). The results showed that RSDs of the intensity of the carbon skeleton stretching modes for R6G and CV were below20%, which indicated this SERS substrate is reproducible and recyclable.