Immoderate nanoarchitectures of bimetallic MOF derived Ni–Fe–O/NPC on porous carbon nanofibers as freestanding electrode for asymmetric supercapacitors.

The logical design and engineering of bimetallic oxide nanomaterials with porous carbon materials have had a significant impact on the development of high-performance electrode materials for energy storage devices in recent years. The vertical and uniform building of porous multimetal nanomaterials on the surface of nanoscale carbon fibers is difficult but not impossible. We present a self-templated metal-organic framework (MOF)-based strategy for the synthesis and assembly of bimetallic oxides/nanoporous carbon nanostructures (Ni–Fe–O/NPC) on porous carbon nanofibers (PCNFs). The vertical alignment of Ni–Fe–O/NPC at PCNFs favors a fast redox reaction by shortening the ion/electrode diffusion path at the electrode-electrolyte interface and helps enhance the overall electrochemical performance. As a freestanding electrode for supercapacitors, it has a high specific capacitance of 1419 F g−1 at 1 A g−1 and good cycling life with capacitance retention of approximately 88.5% after 10,000 cycles. The Ni–Fe–O/NPC@PCNFs-400//Fe 2 O 3 /NPC@PCNFs asymmetric supercapacitor (ASC) achieves a high energy density of 41.3 Wh kg−1 at a power density of 892.2 W kg−1 with a long cycle of life (20,000 cycles) and a high rate capability (78.6%), indicating its potential applications. [Display omitted] • MOF-derived metallic oxides on PCNFs as free-standing electrode materials for ASC. • Tetragonal rodlike Ni–Fe–O/NPC@PCNFs is successfully grown using Ni–Fe-MOF@PCNFs. • Vertical alignment of Ni–Fe–O/NPC at PCNFs provides sufficient redox-active sites. • The assembly of Ni–Fe–O/NPC@PCNFs//Fe 2 O 3 /NPC@PCNFs as an ASC delivers high energy density. [ABSTRACT FROM AUTHOR]