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

Highlights: • NiO/Co₃O₄ nanoheterostructure was fabricated by a simple pyrolysis treatment of nickelocene filled ZIF-67. • The nanoheterostructure present high specific capacitance and excellent cycling stability. • The work provides a novel strategy to prepare metal oxide nanoheterostructure. In this work, a novel NiO/Co₃O₄ nanoheterostructure was fabricated via a simple pyrolysis treatment of nickelocene (NiCp2) filled ZIF-67. With remarkable structural features, the obtained NiO/Co₃O₄ 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/Co₃O₄ 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/Co₃O₄ nanoheterostructure was attributed to its special hierarchical nanoarchitecture, in which the synergistic effect of Co₃O₄ 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.