Metal-organic Framework-derived Nanomaterials As Electrode Materials For Supercapacitor

With the rapid increase in human energy consumption and the severe environmental issues it brought up in the last decades,facilitating clean energy sources such as solar power,wind power,tide power,etc.becomes more and more urgent.However,a common problem for these sustainable energies sources is that they don't exist all the time but obey certain patterns.Hence,energy storage devices that collects these energy from time to time attracts scientists' attention.As one of the most popular energy storage devices,supercapacitors,possessing high power density,long cycle life and very short charging time,makes it widely used in many fields.Nanomaterial,with the high specific area can both facilitate faster reaction rates and larger capacitances.Metal-organic frameworks(MOFs),containing inorganic components(metal ions or metal clusters)and organic components(organic ligands),have been demonstrated as promising templates or precursors to fabricate porous nanostructured material via thermolysis.The objective of this dissertation is to synthesize nanomaterials with unique structures using various MOFs as precursors or templates.The electrochemical performance of as-prepared materials were investigated.The details are as follows:In chapter two,Starfish-shaped porous Co3O4/ZnFe2O4 hollow nanocomposites were fabricated by a stepwise hydrothermal approach,utilizing metal-organic frameworks(MOFs)as precursors and sacrificial templates.The smart integration of Co3O4 and ZnFe2O4 realizes the synergistic effect between Co3O4 and ZnFe2O4.Moreover,the unique porous structure ensures sufficient penetration of the electrolyte and helps the enhanced electrode.The electrode made of Co3O4/ZnFe2O4 is able to work under a large potential window of 1.35 V,exhibiting good capacitive performance in terms of the energy density,specific capacity and cycle life,which are much higher than that of the individual components.In chapter three,MIL-100(Fe)nanospheres were prepared using a step-by-step assembly strategy.The hollow porous carbon spheres were obtained after the calcination.The supercapacitor studies of hollow carbon nanosphere were conducted,and it was found that the hollow structure and the existence of micro-and mesoporous are beneficial to promoting the electrochemical performance.In the last chapter,we report a facile and environmental-friendly glutamic acid-assisted hydrothermal strategy for preparation of ultrathin two-dimensional(2D)?-Ni(OH)2 nanosheets,which exhibit a micron-sized planar area and ultrathin thickness(2.3 nm).We assume a probable formation process based on hydrolysis based on the effect of reaction time and addition of glutamic acid.Due to the unique 2D nanostructure morphology,the ultrathin Ni(OH)2 nanosheets show high capacities,excellent cycling stability and good rate capability when evaluated as an electrode material for supercapacitor.