Conductive cobalt-organic framework nanoboxes for efficient electrochemical oxygen reduction

Abstract

The development of efficient oxygen electrocatalysts and understanding their catalytic mechanism are vitally essential for sustainable energy technologies. Here, hollow conductive metal-organic frameworks nanoboxes (Co-MOF NBs) with quadrilateral Co-N4 units are well-designed and prepared via chemical etching and ligand exchange strategy, and serve as promising catalysts for oxygen reduction reaction (ORR). Atomically dispersed Co-N4 centers with single-electron occupation of the eg orbital (eg∼1) can readily penetrate the antibonding π-orbital of oxygen, thereby facilitating electron exchange between the Co sites and adsorbed oxygen and conferring high ORR activity. The hollow nanostructure ensures efficient charge/mass transfer and well-exposed active centers for Co-MOF NBs. The obtained Co-MOF NBs deliver superior ORR performance with high half-wave potential of 0.88 V and operation durability in 0.1 M KOH. The assembled zinc-air battery with Co-MOF NBs cathode catalyst achieves a maximum power density of 230 mW cm−2, which outperform commercial Pt/C and other reported MOF-based catalysts.