Tuning MOF-Derived Co₃O₄/NiCo₂O₄ Nanostructures for High-Performance Energy Storage

Highly porous Co₃O₄/NiCo₂O₄ nanostructures were synthesized using zeolitic imidazolate framework-67 (ZIF-67) nanocrystals. The oxide composite structure was adjusted by modifying ZIF-67 crystallite size and the pore structure by the coordination modulation method. After forming the zeolite imidazolate framework-67 (ZIF-67)/Ni–Co layered double hydroxide intermediate composite through reaction with nickel nitrate, the intermediate composite was heated in air to result in Co₃O₄/NiCo₂O₄. Nitrogen adsorption was used for pore structure characterization of the template and resultant oxide composite. The maximum capacitance of nanostructured Co₃O₄/NiCo₂O₄ was 770 F g^–1 at a discharge current density of 1 A g^–1 with acceptable cycle stability, maintaining 70% of the initial capacitance after 10,000 charge–discharge cycles.