Hierarchical NiCo2O4@Co-Fe LDH core-shell nanowire arrays for high-performance supercapacitor

Abstract

In this work, hierarchical NiCo2O4@Co-Fe layered double hydroxide (LDH) core-shell nanowire arrays on Ni foam were synthesized by facile hydrothermal and calcination methods. The pre-formed NiCo2O4 nanowires on Ni foam acted as a substrate and then guided the deposition of Co-Fe LDH nanoflakes on their surface to form a highly porous hierarchical core–shell heterostructure. Meanwhile, NiCo2O4 nanowires and Co-Fe LDH nanoflake films were also deposited on Ni foam. The materials were well characterized and used for electrochemical energy storage. The unique core-shell configuration of NiCo2O4@Co-Fe LDH can make full use of the synergistic effects of two components, provide sufficient electroactive sites as well as facilitate the charge transportation process. The as-prepared NiCo2O4@Co-Fe LDH nanowire arrays displayed outstanding electrochemical performances with a high specific capacitance of 1557.5 F g−1 at 1 A g−1. The assembled two-electrode hybrid device NiCo2O4@Co-Fe LDH//activated carbon could deliver an energy density of 28.94 Wh kg−1 at the power density of 950 W kg−1, showing a promising potential in energy storage and conversion.