Experimental and theoretical study of low-dimensional iron oxide nanoparticles and their nanocomposites

Iron oxyhydroxide and oxide nanoparticles have shown potential capabilities in the field of nanoelectronics, clean energy, and biomedicine. The studies of the physical and chemical properties of these nanomaterials are important for understanding the formation and growth mechanisms, interface interactions, and surface behaviors control for functional properties and potential applications.Various iron oxyhydroxides/oxides were primarily investigated in this thesis, including Goethite (α-FeOOH) and Akaganéite (β-FeOOH) one-dimensional (1-D) nanostructures with various aspect ratios under ambient conditions. These iron oxyhydroxide materials are thermally and chemically unstable, therefore can easily convert into hematite (α-Fe2O3) and magnetite (Fe3O4) by calcinations and/or chemical reduction, respectively.To further enhance the functional properties and performance, the nanocomposite composed of the core iron oxyhydroxide/oxide particles and polymer or metal coatings were also investigated. The direct deposition of metal nanoparticles (e.g., gold and platinum) was firstly studied. This method will produce stable nanoparticles, which will be useful for chemical adsorption and catalysis. The synthesis of surfactant, polymer, and silica coated nanocomposites was also considered. This procedure is often used in the low temperature applications because the core-shell structure is favorable especially in the areas of drug-deliveries, biological/chemical separations, and sensors.In order to gain a fundamental understanding of the nanoscale system, it is important to use multiscale theoretical methods validated by experimental techniques. Our research method involves the use of various microscopy, diffraction, and spectroscopy techniques to obtain experimental results. The data is further understood through a computational simulation, which allows further insights into fundamental theories of nanoparticle interactions