Constructing Nitrogen‐Doped Carbon Hierarchy Structure Derived from Metal‐Organic Framework as High‐Performance ORR Cathode Material for Zn‐Air Battery

Abstract

AbstractThe development of efficient and low‐cost catalysts for cathodic oxygen reduction reaction (ORR) in Zn‐air battery (ZAB) is a key factor in reducing costs and achieving industrialization. Here, a novel segregated CoNiPt alloy embedded in N‐doped porous carbon with a nanoflowers (NFs)‐like hierarchy structure is synthesized through pyrolyzing Hofmann‐type metal‐organic frameworks (MOFs). The unique hierarchical NFs structure exposes more active sites and facilitates the transportation of reaction intermediates, thus accelerating the reaction kinetics. Impressively, the resulting 15% CoNiPt@C NFs catalyst exhibits outstanding alkaline ORR activity with a half‐wave potential of 0.93 V, and its mass activity is 7.5 times higher than that of commercial Pt/C catalyst, surpassing state‐of‐the‐art noble metal‐based catalysts. Furthermore, the assembled CoNiPt@C+RuO2 ZAB demonstrates a maximum power density of 172 mW cm−2, which is superior to that of commercial Pt/C+RuO2 ZAB. Experimental results reveal that the intrinsic ORR mass activity is attributed to the synergistic interaction between oxygen defects and pyrrolic/graphitic N species, which optimizes the adsorption energy of the intermediate species in the ORR process and greatly enhances catalytic activity. This work provides a practical and feasible strategy for synthesizing cost‐effective alkaline ORR catalysts by optimizing the electronic structure of MOF‐derived catalysts.