Synthesis And Supercapacitor Performance Of MOFs-based Porus Material

Electrochemical capacitors, also known as supercapacitors,because of their high power density, fast charge and discharge time, long cycle life, has great market potential as energy storage device. Electrode materials play a crucial role in improving the performance of supercapacitor. Metal-Organic frameworks（MOFs） are a class of porous crystalline coordination?based compounds in which metal ions（or metal clusters） are bridged via organic ligands to form infinite network structures. MOFs are considered to be potential precursors for supercapacitor electrode material based on their high surface areas,controllable structures and abundant organic species in their scaffolds.In this work, zinc-based MAF-6 and cobalt-based ZSA^-1 are selected as precursors. Due to the low boiling point of zinc metal, after pyrolysis in an inert atmosphere, a porous carbon material is obtained. And they are used as electrode materials of electric double layer capacitor（EDLC）; Cobalt oxide is an excellent pseudocapacitor electrode material for its variable price, thus we choose a cobalt-containing MOFs as template, the mesoporous Co₃O₄@carbon composites were obtained by controlling calcination conditions. Furthermore, the characterizations of hierarchical porous carbons and mesoporous Co₃O₄@carbon composites were fully developed, including powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, N2 adsorption and Raman spectroscopy.Hierarchical porous carbonswere prepared by usingmicroporous zeolitic metal azolate frameworks（MAF-6） as both template and carbon precursor. After the carbonization, the original shape of the sacrificial MAF-6 has been well preserved, and the sizes of the obtained hierarchical porous carbonsare much smaller than the parent MAF-6. Especially, the HPC1000-5 manifests a high specific capacity(283.4 F·g^-1 at 0.2 A·g^-1) and excellent cycling performance in an alkaline aqueous electrolyte. mesoporous Co₃O₄@carbon composites were prepared through a simple, one-step, carbonization of microporous cobalt-based porous coordination polymer ZSA^-1. After the carbonization,the original octahedral shape of the precursor ZSA^-1 has been well preserved, and the obtained octahedrons consisted of irregular nanoparticles with an average size of 10 nm. The as-synthesized Co₃O₄@carbon composites displayed mesoporous apertures with an average pore size of 3.6 nm. The electrochemical results show that the mesoporous Co₃O₄@carbon composites exhibit a specific capacitance of 205.4 F·g^-1 at a current density of 0.2 A·g^-1.