Preparation Of Ferric Oxide And Its Composite Nanomaterials, And Its Application In Catalysis And Energy Storage

Owing to unique physical and chemical properties, Fe3O4magnetite nanoparticles and its nanocomposites have wide applications in catalysis,energy conversion and storage, catalysis, chemical sensor and so on. In this dissertation, we synthesis Fe3O4using the hydrothermal method and Further process and functionalized it. Finally, their applications either in catalysis or energy storage are investigated.1. Preparation of silver nanostructures on magnetic Fe3O4@C core/shell nanocomposites and application in catalytic reduction reactionsA simply hydrothermal method, using FeCl3·6H2O as the iron resource, NaAc as the precipitation agent, polyvinylpyrrolidone (PVP) as the protective agent, anhydrous sodium acetate (NaAc) as the precipitant, was developed to prepare Fe3O4.MFC composites consist of a magnetic core of Fe3O4microsphere onto which a thin layer of carbon was coated by in-situ carbonization of glucose under hydrothermal condition. And then through in-situ renduction method using MFC as support Ag/MFC.The catalytic activity of the as-prepared Ag/MFC is investigated by photometrically monitoring the reduction of4-nitrophenol and methylene blue by an excess of NaBH4. The kinetic data of both reduction reactions could be explained by the assumption of a pseudo-first-order reaction with regard to4-nitrophenol or methylene blue. The influences of electrolytes and ionic strength on the catalytic reduction rate were studied. Significantly, the Ag/MFC catalysts can be easily separated from the reaction media by applying an external magnet, and can be reused for several cycles.2. Polyaniline-Coated Fe3O4Microspheres and Magnetic Support for Gold Nanoparticles for Catalytic Applicationsa new method was applied to synthesize magnetically responsive Fe3O4@polyaniline(PANI)@Au nanocomposites via a three-step process. superparamagnetic Fe3O4@PANI with well-defined core/shell nanostructure was synthesized in situ surface polymerization method with the assistance of sodium dodecyl sulfonate (SDS).Then, by virtue of electrostatic attraction, as-prepared Au nanoparticles were immobilized on Fe3O4@PANI core/shell composites to avoid the deactivation of catalyst. The catalytic activity of the as-prepared Fe3O4@PANI@Au composites was investigated by monitoring the reduction of Congo red in present of NaBH4. The kinetic data of reduction reactions was explained by the assumption of a pseudo-first-order reaction with regard to Congo red. The influences of electrolytes and surfactants on the catalytic reduction rate were studied. Significantly, Fe3O4@PANI@Au composite catalyst exhibited high catalytic activity, excellent stability and convenient recycling by applying an external magnet.Mostimportantly, this experiment provides a strong platform a strongplatform to explorethe more potentialcatalytic composite in the future.3. Fabrication and electrochemical characteristics of Fe3O4Microspheres and its nanocompositeFe3O4@、Fe3O4@PANI nanocomposites with core-shell structure were synthesized via two-step process. Fe3O4@C@PANI was synthesized via the similar method. The electrochemical performance of Fe3O4@C, Fe3O4@PANI, Fe3O4@C and Fe3O4@C@PANI is investigated using cyclic voltammetry (CV), galvanostatic charge-discharge measurement, and electrochemical impedance spectroscopy by a three-electrode system. The results show that as-prepared nanomaterials are all typical pseudo-capacitance capacitors. In the process of charge-discharge process occurred oxidation-reduction reaction. In addition, the specific capacitance and stability of Fe3O4and its composites were studied. All of them showed good electrochemical properties. So, it demonstrates that the as-prepared nanomatericals can serve as excellent electrode materials for supercapacitors.