Cobalt-Embedded N‑Doped Carbon Nanostructures for Oxygen Reduction and Supercapacitor Applications

Metal–organic
framework (MOF)-derived nanostructures are
portraying a major confront to the quest for high-performing electrocatalysts
for energy conversion and storage devices largely because of their
tunable synthesis, high surface area, and presence of various heteroatoms
depending upon the choice of ligands used as precursors. In this regard,
multifunctional electrode material development with high performance
is a contemporary trend. We report an innovative integrated nanostructure
of Co-NC3 (Co-MOF annealed at 700 °C for 3 h under Ar) bestowed
with admirable potential, derived from a newly designed Co­(II)-based
MOF comprising benzene-1,3,5-tricarboxylic acid and 1,10-phenanthroline.
The Co-NC3 nanostructure derived from Co-MOF was found to be a highly
efficient catalyst for the oxygen reduction reaction with onset potential
(0.90 V vs RHE) and half-wave potential (0.81 V vs RHE) comparable
to those for the commercial 20 wt % Pt/C catalyst (0.91 and 0.83 V
vs RHE). Next, the same catalyst was explored as a commendable energy-storage
material for supercapacitors with a specific capacitance value of
310 F/g at a 0.5 A/g current density. We fabricated a solid-state
asymmetric supercapacitor device from Co-NC3 and lit light-emitting
diodes of 1.8 V each using three such supercapacitors in series. For
the first time, a Co-MOF-derived supercapacitor was deployed successfully
in a solar photovoltaic-based sensor node system.