Structural and interface engineering of Co nanocatalysts induce boosting the electrochemical performance for rechargeable zinc-air battery

Abstract

The development of highly-efficient bi-functional catalysts for Zn-air battery is of importance for sustainable energy-storage field. Rational utilization the integral advantages of metal-organic frameworks and traditional templates is an effective strategy to achieve high performance multi-functional catalysts. Herein, the di-nuclear Co-Zn-MOF was synthesized on the surface of polystyrene (PS) with a facile method, then the porous N, P co-doped carbon encapsulated Co-based catalysts were developed by calcining the PS@Co-Zn-MOF template followed by acid-mist treatment. The characterization results reveal that acid-mist treatment strategy can efficiently modify the surface feature, and remove the surface-adsorbed and unstable metal nanoparticles, thus improving the stability of catalysts. Moreover, this work also proves that low concentration acid-mist treatment can improve the graphitization degree, while high concentration acid can lead to the increase of defective carbon. With this strategy, the obtained Co@PNC-850-0.1H catalyst achieves an impressive enhanced ORR/OER performance, and the potential difference between ORR and OER is only 0.734 V at 0.1 M KOH condition. Additionally, the Co@PNC-850-0.1H based aqueous and all-solid-state Zn-air batteries (ZABs) also deliver excellent performances with extraordinary power density (194.3 mW·cm−2; 70.7 mW·cm−2), high specific capacity (779.7 mAh·g−1@10 mA·cm−2; 723 mAh·g−1@5 mA·cm−2), and ultra-high stability.