Facile Synthesis of Metal-Organic Framework-Derived CoSe₂ Nanoparticles Embedded in the N-Doped Carbon Nanosheet...

Metal-organic framework (MOF)-derived composites of transition metal oxides and porous carbon show great potential for energy storage applications. Selenylation is an effective strategy to improve the electrochemical properties of electrode materials. A facile one-step derivation and selenylation of MOFs is proposed here to obtain CoSe₂ nanoparticles embedded into an N-doped carbon skeleton material (CoSe₂/NC). Moreover, the composite is directly grown on nickel foam as nanosheet arrays, rather than on other materials as powders. The CoSe₂/NC electrode with special construction exhibits a high capacity of 120.2 mA h g^-1 at 1 A g^-1 and an excellent cyclic ability of 8% loss after 10,000 cycles. An asymmetric supercapacitor CoSe₂/NC-NF//AC displays a maximum energy density of 40.9 W h kg^-1 at 980 W kg^-1. Moreover, the device has demonstrated that it can successfully charge a mobile phone. The outstanding performance indicates promising potential of CoSe₂/NC-NF electrodes for supercapacitors.