Engineering Hierarchical Nickel Cobalt Metal-Organic Frameworks Through Metal Ion Modulation for High-Performance...

Recent advances on metal-organic framework (MOF)-based electrodes have led to significant breakthroughs in the energy storage device sector. In this study, we explored the binder and conducting carbon free synthesis of nickel-cobalt MOF electrodes on nickel foam substrate via the simple successive ionic layer adsorption and reaction (SILAR) technique. The concentration of Ni and Co precursor [molar ratio] is systematically varied to obtain a series of NiCo-MOF-based electrodes. An excellent charge storage performance for NCM3 (Ni:Co, 1:1) electrode was revealed in a three-electrode system, which can be attributed to homogeneous interconnected platelet-like morphology. The NCM3 electrode exhibited a specific capacity (Csp) of 934 C g^-1 at 2 mA cm^-2 current density. To show the practical applicability, a hybrid aqueous supercapacitor device (HASD) with a widened potential window was fabricated, comprising NCM3 as the positive electrode and reduced graphene oxide (rGO) as the negative electrode (NCM3//KOH//rGO). HASD delivered remarkable specific capacitance (Sc) of 128 F g^-1 and maximum specific energy (SE) of 45.58 Wh kg^-1 at 2 mA cm^-2. The highest specific power (SP) of 3840 W kg^-1 was achieved at 6 mA cm^-2. Thus, SILAR-based approach presents a promising route for the synthesis of high-performance NiCo-MOF-based electrodes.