Engineering novel NiCoZn oxide@carbon porous framework/NiCo2S4 composites derived from MOFs for high-performance hybrid supercapacitors

Abstract

The rising demand for sustainable energy has intensified research on supercapacitors that can achieve high energy density, rapid power delivery, and excellent cycling durability. To achieve these attributes, considerable research has been directed to engineering diverse electrode materials, including carbon-based structures, transition metal oxides, together with their sulfide and phosphide counterparts, and conducting polymers. Metal Organic Frameworks (MOFs) have emerged as potential electrode materials driven by their tunable porosity and high surface area, yet their low intrinsic conductivity and structural instability limit direct application in supercapacitors. We have reported a hydrothermally synthesized trimetallic NiCoZn-MOF and calcined this to produce a metal-oxide/carbon framework. This framework was utilized for the in situ growth of NiCo₂S₄ nanoparticles. The resulting metal-oxide/carbon framework@NiCo₂S₄ nanocomposite combines the electrical conductivity and redox activity of sulfides along with the stability and high surface area of the MOF-derived matrix. The optimized electrode (1 wt% calcined-MOFs/1.5 wt% NiCo₂S₄) exhibited a specific capacity (Q_s) of 458.5 C g⁻¹ at 0.5 A g⁻¹. The assembled asymmetric supercapacitor achieved an energy density (E_d) of 76 W h kg⁻¹ at a power density (P_d) of 700 W kg⁻¹ and a coulombic efficiency of 98%. It retained 80.01% capacitance after 5000 cycles. Dunn's analysis indicated that charge storage was primarily diffusion controlled. These findings demonstrate the superior performance of MOF-derived sulfide nanocomposites as effective electrode materials for application of high-performance supercapacitors.