In situ construction of NiFe2O4/ZIF-67 hybrid nanostructures with optimized interfacial interaction for asymmetric supercapacitors

Abstract

Designing a heterostructure is an effective route for improving the electrochemical performance of hybrid supercapacitor electrodes. In this study, a hybrid nanostructure comprising NiFe 2 O 4 (NFO) nanospheres and rhombic dodecahedral cobalt-based metal-organic frameworks (ZIF-67) was prepared and optimized via an in situ one-pot synthesis route. Structural and morphological characterization confirms that the NFO was uniformly distributed in the framework without compromising the structural integrity of bare ZIF-67 in the hybrid structure, thereby enhancing intimate contact and efficient charge transfer across the interface. Notably, the optimized hybrid 20NFO/ZIF-67 nanostructure displays a specific capacity of 726 Cg -1 at 1 Ag -1 with relatively small charge transfer and series resistance in a three-electrode system configuration. An asymmetric device fabricated from 20NFO/ZIF-67 and activated carbon (AC) achieves a specific energy of 30.63 Wh kg -1 and a specific power of 875 W kg -1 , retaining 74.5% capacitance after 10,000 cycles. The incorporation of NFO significantly improves the electrochemical activity of ZIF-67, owing to the synergistic redox activity effects and enhanced electron transport at the NFO/ZIF-67 interface. This work promotes efficient energy storage through the design of hybrid nanostructures with optimized interfacial interaction. • In situ one-pot synthesis facilitates uniform integration of NiFe 2 O 4 nanospheres within the ZIF-67 framework. • Intimate NFO/ZIF-67 interfacial contact facilitates efficient electron transport and synergistic redox activity. • The optimized hybrid electrode delivers a high specific capacity of 726 C g -1 at 1 A g -1 . • Asymmetric hybrid device exhibits a specific energy of 30.63 Wh kg -1 and 74.5% capacity retention after 10,000 cycles.