Hierarchical Porous Multi-Heterometallic Co ₂ MnS ₄ @NiFe ₂ O ₄ /CC Heterostructures Fabricated via MOF Template for High-Performance Hybrid Supercapacitors

Bimetallic oxide/sulfide (BMO/BMS) heterostructures have emerged as attractive electrode materials for supercapacitors, leveraging the synergistic effects of high redox activity from BMO and high electrical conductivity from BMS. However, the majority of existing approaches for constructing BMO/BMS yield homometallic heterostructures, suffering from limited redox activity and inadequate interfacial electronic interactions. Herein, NiFe-MOF-74 was employed as a sacrificial template to fabricate hierarchical porous multimetallic Co 2 MnS 4 @NiFe 2 O 4 /CC heterostructures via in situ growth on conductive Co 2 MnS 4 /CC nanowires followed by calcination. The NiFe-MOF-74 template not only introduces heterometals but also enables optimization of the sulfide-to-oxide ratio through precise modulation of the NiFe-MOF-74 content. In the optimized (Co 2 MnS 4 ) 0.48 @(NiFe 2 O 4 ) 0.52 /CC, the highly redox-active NiFe 2 O 4 shell synergizes with the highly conductive Co 2 MnS 4 core to provide rich and diverse active sites alongside efficient charge transport pathways. The enhanced electronic interactions at heterometallic BMO/BMS heterointerfaces accelerate charge/ion transfer kinetics, while the hierarchical porous structure exposes sufficient redox-active sites and establishes efficient ion diffusion pathways. This design achieves an exceptional specific capacity of 1197 C·g –1 at 1 A·g –1 with 76.6% rate retention (10 A·g –1 ). The assembled flexible (Co 2 MnS 4 ) 0.48 @(NiFe 2 O 4 ) 0.52 /CC//NC/CC device delivers a high energy density of 76.5 Wh·kg –1 at 750 W·kg –1, retaining 93.86% capacity after 10,000 cycles, outperforming most reported composites based on BMO or BMS.