Polyoxometalate@Metal-Organic Framework-Derived Fe-Co-Mo/NC: An Advanced Electrocatalyst for Zinc-Air Batteries

Abstract

To meet the increasing demand for advanced energy conversion systems, zinc-air batteries (ZABs) have garnered significant attention as promising electrochemical energy storage and conversion devices. However, their practical application has been impeded by several intrinsic limitations, such as sluggish oxygen reduction reaction (ORR) kinetics at the air cathode, substantial overpotentials, and insufficient operational stability. In this study, we synthesized a defective Fe-Co-Mo/NC catalyst by encapsulating an Anderson-type polyoxometalate into the pores of Fe-ZIF-8. The strategic incorporation of polyoxometalate into the metal-organic framework (MOF) matrix not only enhances structural defect density but also suppressing nanoparticle aggregation, thereby significantly increasing the number of accessible active sites. Moreover, the Co-Mo heterometallic composition of the polyoxometalate generates multifunctional catalytic centers that exhibit synergistic electronic interactions, collectively boosting electrocatalytic performance. As a result, the Fe-Co-Mo/NC electrocatalyst demonstrates remarkable bifunctional activity and durability, achieving a peak power density of 150.9 mW cm-2, a specific capacity of 787.24 mAh gZn-1, and stable cycling performance exceeding 300 hours in ZAB applications. This work presents a novel strategy for developing polyoxometalate-based MOF materials as highly efficient electrocatalysts.