Synthesis And Properties Characterization Of Nonspherical Hollow Nanostructures

Three-dimensional (3D) nanostructures obtained by bottom-up approaches have been a focus of scientific research. The morphologies of3D structures have impacts on their properties, which may bring new applications. However, it remains quite difficulty in preparing delicate shaped3D hollow nanostructures with uniform coatings around high curvature surfaces. This dissertation focus on fabrication of hollow polyhedral nanostructures with MOFs as the sacrificial template, providing a new effective solution for preparing3D hollow nanostructures with delicate shapes.1. Synthesis of novel ZnS nanocages utilizing ZIF-8polyhedral templateTruncated rhombic dodecahedral ZIF-8nanocrystals have been fabricated with acetate as a modulating ligand. And with Zn-containing ZIF-8nano-crystals as templates, utilizing ethanol with trace water to dissolve ZIF-8templates and control S2-anions releasing, we have successfully fabricated nonspherical hollow-structured ZnS, which demonstrates that the method is facile and feasible. The nanocages are composed of nanoparticles with the size of2-3nm and the thickness for the cage wall is around20nm. The surface area is150m2g-1. The optical properties of ZnS nanocages and individual ZnS nanoparticles are characterized. The study opens up a new way for synthesizing3D hollow nanostructures. And in view of the enormous kind of MOFs with different compositions and morphologies, there is doomed to be a great opportunity to further develop3D nanostructures with numerous morphologies and structures.2. LDH Nanocages Synthesized by MOF Templates and the High Performance as SupercapacitorThree hollow rhombic dodecahedral LDH nanocages which are composed of thin nanoplatelets have been synthesized with ZIF-67nanocrystals as templates. Nanosheets assembled with an edge-to-face stacking constitute the polyhedral shell which well inherits the morphology and dimension of the ZIF-67templates. Specifically, it is crucial for the formation of LDH nanocages to simultaneously control hydrolysis of metal ions, acid etching of insoluble templates and oxidation of divalent cobalt. And the Ni-Co LDH nanocages exhibit superior pseudocapacitance property due to the novel hierarchical and submicroscopic structures. This study not only provides an opportunity to explore the enhanced properties of the LDHs with complex structures, but also further confirms that the method of synthesizing non-spherical hollow structures with MOF nanocrystal templates is feasible. And in view of the enormous variation of MOFs with different compositions and morphologies, it would be a promising way for fabricating an array of complex nanostructures which would present prospective properties in various applications.3. Synthesis of amorphous cobalt sulfide polyhedral nanocages for high performance supercapacitorsAmorphous cobalt sulfide polyhedral nanocages have been fabricated by utilizing ZIF-67nanocrystals as the templates. The nanocages are composed of nanoparticles and the thickness for the cage wall is around60nm. The surface area is96m2g-1.The precise control of the S2-hydrolyzing and ZIF-67template dissolving is crucial for fabricating high-quality CoS nanocages. Electrochemical characterization shows that the CoS nanocages exhibit high specific capacitance, owing to its amorphous phase and novel structures.