NiO/Co3O4 nanoheterostructure derived from nickelocene filled ZIF-67 for supercapacitors.

In this work, a novel NiO/Co 3 O 4 nanoheterostructure was fabricated via a simple pyrolysis treatment of nickelocene (NiCp2) filled ZIF-67. With remarkable structural features, the obtained NiO/Co 3 O 4 hybrids exhibit high specific capacitance of 405 F g -1  at 1 A g −1 and high cycling stability (97.4% after 1000 cycles at 15 A g −1 ). Asymmetric supercapacitors (ASCs) were fabricated using the NiO/Co 3 O 4 heterostructure as the positive electrode and active carbon as negative electrode. The operation voltage of ASCs is expanded to 1.5 V in aqueous electrolyte, revealing high energy density (23.8 Wh kg −1 at a power density of 0.75 kW kg −1 ) and high capacitance retention (97.9% after 1000 cycles). The excellent electrochemical performance of the NiO/Co 3 O 4 nanoheterostructure was attributed to its special hierarchical nanoarchitecture, in which the synergistic effect of Co 3 O 4 and NiO to supply more pathways for accelerating fast electron and ion transfer. This functionalized MOF-driven strategy pave the way to the preparation of various metal oxide nanoheterostructures by varying the type of MOFs and fillers. [ABSTRACT FROM AUTHOR]