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.