| Supercapacitor is an efficient and paratical energy storage device due to its high specific capacitance, long cycling life, wide opercating temperatures range and free service. The electrochemical performance of supercapacitors depends on the electrode materials. Activated carbon was the first to be applied to the electrode material for supercapacitors because of its low cost, simple preparation and electrochemical stability. In recent years, metal oxides, conducting polymers and other materials are increasingly attracting attention. As a new type of porous material, Metal-organic frameworks(MOFs) not only have high specific surface area but also comprise active metal ions or atom clusters in the structure. These characteristics make MOFs have a large application potential for high performance supercapacitors. In recent years, a limited number of MOFs are investigated for supercapacity property as supercapacitor electrode materials. In this paper, ZIF-8 and ZIF-67 were chosed for research and they were used as carriers for other electrode materials. Structural analysis were carried out using powder X-Ray Diffractomer(XRD), Fourier Transform Infrared(FT-IR), N2 adsorption-desorption studies, Scanning Electron Microscope(SEM) and transmission electron microscope(TEM); The properties of the electrodes were studied by cyclic voltammetry(CV), chronopotentiometry, electrochemical impedance spectroscopy(EIS) and cycle life test. The main contents are as follows:(1) ZIF-8 and ZIF-67 were used as supercapacitor electrode materials in an aqueous electrolyte system for the first time. The cyclic voltammograms show that the materials have high electrochemical activity and good reversibility in 6 M KOH electrolyte. The specific capacitances of them reach 96 and 65 F g-1 at a scan rate of 5 m V s-1, respectively. For ZIF-8, the specific capacitance can reach 185 F g-1 by calcination at 723 K under nitrogen without adding additional carbon source.(2) SO42-/Ti O2, SO42-/Sn O2, SO42-/Zr O2 and SO42-/Fe2O3 were prepared and used as electrode materials in supercapacitor. The specific capacitances of them reach 30 F g-1, 19 F g-1, 21 F g-1 and 28 F g-1 in 0.5 M H2SO4 electrolyte, at a scan rate of 5 m V s-1, respectively.(3) ZIF-8 was an excellent carrier and acts as the host for the growth of other active substance forming electrode composite materials to improve the electrochemical properties of the active substance itself. Herein, Sn O2 quantum dots, Ni-B amorphous alloy and Ni2CO3(OH)2 were prepared and ZIF-8 acts as a carrier to support them. They all as the electrode material show pseudocapacitance performance in 6 M KOH electrolyte. The specific capacitance of composites can reach 931 F g-1, 866 F g-1, 851 F g-1 at a scan rate of 5 m V s-1. However, calculated specific capacitance values of the Sn O2 quantum dots, Ni-B amorphous alloy and Ni2CO3(OH)2 were 241 F g-1, 563 F g-1 and 668 F g-1, respectively, at the same scan rate. All the results implied that they have a potential for electrode material in supercapacitor.(4) As ZIF-67 was isostructural to ZIF-8 replacing the Zn atoms with Co, it is expected that ZIF-67 can be also used as a supercapacitor material. In this paper, Ni2CO3(OH)2 and Ni C2O4?2H2O were prepared and ZIF-67 acts as a carrier to support them for electrode materials in supercapacitor. The results show that they have pseudocapacitance performance in 6 M KOH electrolyte. The specific capacitance of composites can reach up to 1037 and 1020 F g-1 at scan rate of 5 m V s-1. But the specific capacitance value of Ni2CO3(OH)2 and Ni C2O4?2H2O were 668 F g-1 and 870 F g-1. All the results show that they were promising materials for supercapacitor. |
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