“Fence”\nEffect Enabling a Metal–Organic\nFramework-Derived Single-Atom Co–N–C Catalyst for High-Performance\nZn–Air Batteries

It offers bright prospects to develop non-Pt group metal\n(non-PGM)\nelectrocatalysts in the area of energy storage and conversion. Herein,\nwe reported a simple spatial isolation strategy to synthesize Co-based\nelectrocatalysts, using partially substituted Zn atoms in a ZnCo-ZIF\nprecursor. The “fence” effect that originated from the\npartially substituted Zn atoms can yield a better isolation of Co\natoms, achieving selective loading of Co species on nitrogen-doped\nporous carbon varying from nanoparticles to single atoms. The low\nboiling point of Zn enables abundant porous structures to the N-doped\ncarbon substrate after pyrolysis. The best performing single-atom\nCo catalyst (Co-SAs/N–C) exhibits excellent oxygen reduction\nreaction activity in alkaline media. As an illustration, the rechargeable\nliquid Zn–air battery incorporating the Co-SAs/N–C catalyst\ndemonstrates a substantial open circuit voltage of 1.49 V, a high\nspecific capacity of 689.3 mAh g<sup>–1</sup>, and remarkable\ncycling stability over 200 h. This study paves the way for the strategic\ndevelopment of non-PGM electrocatalysts in battery applications.