Electrochemical kinetics and energy storage performance of 3D hierarchical CuFeS2@rGO micro-flower electrodes

Abstract

Among various candidates, hierarchical nanostructured composites integrating transition-metal chalcogenides with conductive carbon frameworks have emerged as promising platforms due to their enhanced electrochemical activity and rapid charge-transport properties. A three-dimensional hierarchical micro-flower architecture of copper iron sulphide (CuFeS₂) integrated with reduced graphene oxide (rGO) is successfully developed, a porous composite architecture that promotes ion diffusion and is evaluated as a high-performance pseudocapacitive electrode material. The CuFeS₂@rGO composite is synthesised via a facile two-step hydrothermal approach, yielding a porous and interconnected structure that facilitates efficient electrolyte accessibility and charge transport. Electrochemical investigations conducted in 1 M aqueous LiOH within a three-electrode configuration reveal that the composite exhibits superior charge storage characteristics, arising from the synergistic interplay between surface-controlled pseudocapacitance of CuFeS₂ and electric double-layer capacitance contributed by rGO. Notably, the CuFeS₂@rGO electrode delivers a high specific capacitance of ∼1160 F g⁻¹ at 1 A g⁻¹, significantly outperforming pristine CuFeS₂ (308 F g⁻¹). In addition, the composite demonstrates excellent cycling stability, indicating its robustness for long-term operation. A symmetric supercapacitor device assembled using CuFeS₂@rGO electrodes exhibits remarkable energy and power densities, along with outstanding cyclic durability, retaining 96.03% of its initial capacitance after 10 000 charge–discharge cycles. These findings highlight the strong potential of earth-abundant CuFeS₂-based hybrid architectures for sustainable, cost-effective, next-generation high-performance supercapacitor applications.