Single Co Atoms Anchored in Porous N‑Doped\nCarbon for Efficient Zinc−Air Battery Cathodes

Abstract

Exploration\nof cheap, efficient, and highly durable transition-metal-based\nelectrocatalysts is critically important for the renewable energy\nchain, including both energy storage and energy conversion. Herein,\nwe have developed cobalt (Co) single atoms anchored in porous nitrogen-doped\ncarbon nanoflake arrays, synthesized from Co-MOF precursor and followed\nby removal of the unwanted Co clusters. The well-dispersed Co single\natoms are attached to the carbon network through N–Co bonding,\nwhere there is extra porosity and active surface area created by the\nremoval of the Co metal clusters. Interestingly, compared with those\nelectrocatalysts containing excess Co nanoparticles, a single Co atom\nalone demonstrates a lower oxygen evolution reaction (OER) overpotential\nand much higher oxygen reduction reaction (ORR) saturation current,\nshowing that the Co metal clusters are redundant in driving both OER\nand ORR. Given the bifunctional electrocatalytic activity and mechanical\nflexibility, the electrocatalyst assembled on carbon cloth is employed\nas the air cathode in a solid-state Zn–air battery, which presents\ngood cycling stabilities (2500 min, 125 cycles) as well as a high\nopen circuit potential (1.411 V).