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

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 Co-3[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 Co-3[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 568Fg(-1) at 0.5Ag(-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. (C) 2017 Elsevier Ltd. All rights reserved.