MnO2 Nanoflowers Decorated on ZIF-8-ZnO with Ni Foam Supportfor High-Performance Supercapacitors

Graphical A binder-free electrode was constructed by decorating MnO 2 nanoflowers onto the hybrid material of ZIF-8/ZnO, as derived from ZIF-8 via pyrolysis. Both the composite electrode and the NF/ZIF-8-ZnO/MnO 2 //activated carbon (AC) asymmetric supercapacitor demonstrate excellent electrochemical performance, showing that NF/ZIF-8-ZnO/MnO 2 is a promising candidate for supercapacitors due to the synergistic contribution of ZIF-8, ZnO and MnO 2 . In this study, ZIF-8 (Zn(MeIn) 2 , MeIn=2-methylimidazole) was synthesized directly on Ni foam with the use of polydopamine (PDA). By following a hydrothermal process, MnO 2 nanoflowers were decorated on the hybrid material of ZIF-8/ZnO, as derived from ZIF-8 via pyrolysis at 500 °C under nitrogen flow. The produced binder-free electrode (NF/ZIF-8-ZnO/MnO 2 ) demonstrated an excellent electrochemical performance for supercapacitors, including a specific capacitance of 2005 F g −1 at 2 A g −1 and a fairly high cycling stability (90.74% retention after 4000 cycles). Furthermore, a NF/ZIF-8-ZnO/MnO 2 //activated carbon (AC) asymmetric supercapacitor showed an energy density of 70.57 Wh kg −1 given a power density of 112.45 kW kg −1 . These results demonstrate that NF/ZIF-8-ZnO/MnO 2 is a promising candidate for supercapacitors due to the synergistic contribution of ZIF-8, ZnO and MnO 2 .