Synthesis Of Iron-based Hierarchical Structures For Applications In Water Treatment And Lithium-ion Batteries

This dissertation focuses on synthesis and applications of iron based hierarchicalstructures. Controllable synthesis strategies of micron/nano sized functional materialsare exploited in order to solve the universal problems of environmental pollution andenergy shortage. On one hand, fabrication processes with advantages of low cost,benign and environment friendly are exploited to achieve large scale preparation ofiron based micron/nano sized materials. On the other hand, many efforts are made toinvestigate their applications in many important areas such as water treatment andlithium ion batteries. Specific research contents are shown as follows.A novel hollow urchin like α FeOOH hierarchical structure was fabricated via aone pot hydrothermal procedure without using any templates, surfactants or organicraw materials. An inside out amorphous ripening mechanism was proposed to unravelits structural evolution. The kinetics, equilibrium and thermodynamics of its adsorptiveremoval of Cr(VI) from wastewater were comprehensively investigated. Theadsorption process was proved to be spontaneous with both physical and chemicalcharacteristics.A facile glycerol assisted hydrothermal method was employed to fabricate a3D hierarchical structure of FeCO3which was comprised of numerous submicronrhombohedrons. The relationship between exposed surfaces and its morphology wasinvestigated to reveal the formation mechanism of the hierarchical structure.Electrochemical performances of the as synthesized FeCO3were tested in a Li/FeCO3cell. Cyclic voltammogram (CV) measurements were carried out to reveal the energystorage mechanism. Reversible specific capacity, cycling performance and ratecapability of the FeCO3hierarchical structure were analyzed by discharging andcharging at different current densities. Electrochemical impedance spectroscopy (EIS)measurements were carried out to reveal the possible reason of its excellentelectrochemical performance.Mild hydrothermal reaction and solvothermal reaction were used to synthesize theiron oxides or their precursors with hollow structures, involving Fe3O4hollow spheres,α Fe2O3hollow nanotubes as well as core shell iron alkoxide. The phases andmorphology of the hollow structures were characterized by X ray diffraction (XRD),field emission scanning electron microscopy (FE SEM) and transmission electronmicroscopy (TEM), respectively.