Three-dimensional hollow CoS2 nanoframes fabricated by anion replacement and their enhanced pseudocapacitive performances

- 3D hollow CoS2 nanoframes (HCSN) have been fabricated by anion replacement.
- 3D HCSN exhibit uniform broken hollow structure with large specific surface area.
- High specific capacitance and good cycling stability are obtained in these 3D HCSN.

Three-dimensional (3D) hollow CoS2 nanoframes (HCSN) have been fabricated by partial anion replacement of Co-based Prussian blue (PB) nanocubes. The initial self-assembled Co-based PB nanocubes can be converted to hollow Co3[Fe(CN)6]2 nanostructures by corrosion reactions with thioacetamide (TAA) under suitable hydrothermal environment. The pure CoS2 are precipitated simultaneously on the surfaces of hollow Co3[Fe(CN)6]2 nanostructures by ion replacement of [Fe(CN)6]3− in Co-based PB nanocubes with S2− in TAA to form the 3D HCSN. The as-synthesized 3D HCSN exhibit large specific surface area due to their uniform broken hollow structure with good dispersion, which results in their good electrochemical performances including a high specific capacitance of 568 F g−1 at 0.5 A g−1 and good cycling stability with 88.3% specific capacitance retention after 5000 cycles. The asymmetric supercapacitor made from the 3D HCSN can present a high energy density of 32.3 Wh kg−1 at a power density of 4 kW kg−1. These 3D HCSN also shows good structural stability and low density, which further promotes their potential application in high-performance supercapacitors.

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