Synthesis of Fe₃O₄/FeS₂ composites via MOF-templated sulfurization for high-performance hybrid supercapacitors

The development of advanced anode materials for supercapacitors is crucial for driving innovation in the field of new energy technologies. Although iron-based materials exhibit significant potential, their electrical conductivity and cyclic stability remain challenges. In this study, Fe3O4/FeS2 composites were successfully synthesized using a sacrificial MOF template and a solid-state sulfurization process. The composite preserved the original morphology of Fe-MOF, while numerous nanoscale particles were generated through heterogeneous sulfurization. Notably, the SMFO-2 composite exhibited a specific capacity of 208.5 mAh g−1 at a current density of 1 A g⁻¹. When integrated into a hybrid supercapacitor (HSC) with SMFO-2 serving as the anode and super-electric activated carbon (AC) as the cathode, the device exhibited excellent electrochemical performance. Specifically, it achieved a capacity retention rate of 78.6 % after 10,000 charge-discharge cycles at 2 A g⁻¹. Furthermore, the HSC achieved an optimal energy density of 28.8 Wh kg⁻¹ at a power density of 375 W kg⁻¹, successfully powering a small bulb, highlighting its strong potential of the Fe3O4/FeS2 composite for real-world practical applications. [Display omitted] •Fe3O4 /FeS2 and FeS2 materials with withered vine morphology were prepared using a sacrificial MOF template and sulphuration.•The MOF precursor is calcined at high temperatures to provide electrical conductivity and stability for Fe3O4 /FeS2.•Fe3O4 /FeS2 composites have better electrochemical properties than FeS2 single components•The hybrid supercapacitor is assembled with Fe3O4 /FeS2 composite material as the cathode and stable activated carbon material as the anode.