Flower-like Ni3(NO3)2(OH)4@Zr-metal organic framework (UiO-66) composites as electrode materials for high performance pseudocapacitors

Zr-metal organic frameworks (Zr-MOFs, UIO-66) as a kind of crystalline porous material possess controllable porous structure and strong thermal stability up to 753 K. In this paper, we synthesized Ni-3(NO3)(2)(OH)(4), Zr-MOF with high specific surface area (1073 m(2) g(-1)) and Ni-3(NO3)(2)(OH)(4)@Zr-MOF composite for pseudocapacitor material. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were taken to characterize the structure and morphology of Ni-3(NO3)(2)(OH)(4), Zr-MOF, and Ni-3(NO3)(2)(OH)(4)@Zr-MOF. The porous structure of Zr-MOF favors the utilization of the active material Ni-3(NO3)(2)(OH)(4) and interfacial charge transport and provides short diffusion paths for ions, which results in a high specific capacitance. Electrochemical properties are evaluated by cyclic voltammetry (CV) and galvanostatic charge/discharge measurement. A maximum specific capacitance (SC) of 992 F/g was obtained from CV at a scan rate of 5 mVs(-1), which is higher than Zr-MOF (similar to 134 F g(-1)) and Ni-3(NO3)(2)(OH)(4) (similar to 753 F g(-1)). Meanwhile, the Ni-3(NO3)(2)(OH)(4)@Zr-MOF composite electrode exhibits a good cycling stability over 3000 cycles.