Nanowire-core/double-shell of NiMoO₄@C@Ni₃S₂ arrays on Ni foam: insights into supercapacitive performance and capacitance degradation

The one-dimensional-core/double-shell arrays on Ni foam were prepared by the hydrothermal, carbonized and electrodeposition processes, consisting of NiMoO₄ nanowire as a core, an ultrathin carbon layer as an internal shell and Ni₃S₂ nanosheets an external shell (abbr. NiMoO₄@C@Ni₃S₂), respectively. The ternary heterostructure demonstrates the synergistic effect on the dimensional, interface, surface structures and compositions, resulting from the ordered and functionalized architectures. Therefore, the NiMoO₄@C@Ni₃S₂ electrode integrated the advantages of the electron transfer, electrolyte penetration and ion diffusion. The asymmetric supercapacitor exhibited a high energy density of 1.29 mW h cm⁻³ at a power density of 13.99 W cm⁻³. Furthermore, we compared the changes in composition, structure and morphology before and after 3000 cycles using the three electrode system. These observations demonstrated that the dissolution of NiMoO₄@C@Ni₃S₂ induced the decay of capacitance and cycling stability, suggesting that we can further develop a strategy to consolidate the electrode structure. (paper)