Hollow carbon shell-confined CoSe2/Ni3Se4 nanoparticles anchored on rGO for enhanced charge storage and stability in supercapacitors.

Simultaneously achieving high charge-storage capability and long-term cycling stability remains a major challenge for supercapacitor electrodes. Herein, a hierarchical CoSe2/Ni3Se4@HCS-rGO electrode was rationally designed by confining CoSe2/Ni3Se4 nanoparticles within hollow carbon shells anchored on reduced graphene oxide (rGO). The hollow carbon shell (HCS) provides accessible inner and outer surfaces and shortened ion-transport pathways, while the CoSe2/Ni3Se4 heterostructure offers abundant redox-active sites for enhanced Faradaic charge storage. Meanwhile, the rGO framework establishes continuous conductive pathways and helps maintain the structural integrity of the hollow architecture. Benefiting from the complementary functions and synergistic integration of these components, the optimized electrode, CoSe2/Ni3Se4@HCS-rGO, delivered a high specific capacitance of 1168.9 F g-1 at 1 A g-1 and retained 93.8% of its initial capacitance after 10,000 charge-discharge cycles. The results demonstrate that the hierarchical integration of hollow carbon, bimetallic selenides, and rGO is an effective strategy for simultaneously enhancing charge storage, ion/electron transport, and cycling stability.