Introducing CuCo2S4 Nanoparticles on Reduced Graphene Oxide for High-Performance Supercapacitor

In this work, a bimetallic sulfide-coupled graphene hybrid was designed and constructed for capacitive energy storage. The hybrid structure involved decorating copper–cobalt–sulfide (CuCo2S4) nanoparticles onto graphene layers, with the nanoparticles anchored within the graphene layers, forming a hybrid energy storage system. In this hybrid structure, rGO can work as the substrate and current collector to support the uniform distribution of the nanoparticles and provides efficient transportation of electrons into and out of the electrode. In the meantime, CuCo2S4-active materials are expected to offer an evident enhancement in electrochemical activities, due to the rich valence change provided by Cu and Co. Benefiting from the integrated structure of CuCo2S4 nanoparticles and highly conductive graphene substrates, the prepared CuCo2S4@rGO electrode exhibited a favorable capacitive performance in 1 M KOH. At 1 A g−1, CuCo2S4@rGO achieved a specific capacitance of 410 F g−1. The capacitance retention at 8 A g−1 was 70% of that observed at 1 A g−1, affirming the material’s excellent rate capability. At the current density of 5 A g−1, the electrode underwent 10,000 charge–discharge cycles, retaining 98% of its initial capacity, which indicates minimal capacity decay and showcasing excellent cycling performance.