Composition regulation of transition metal electrocatalysts derived from zeolite imidazolate frameworks for Zn-air batteries

Zinc-air batteries (ZABs) have attracted much attention in energy storage and conversion because of their low cost, safety, eco-friendliness, and high energy density. However, the sluggish oxygen redox reaction hampers the overall performance of the batteries. It is crucial to deploy cost-effective and conversion-efficient air electrodes to replace precious metal electrocatalysts (Pt/Ru). Electrocatalysts (M-N-C) formed by loading transition metal atoms in nitrogen-doped carbon carriers (N-C) have the advantages of high activity, structural stability, and outstanding electrical conductivity. Zeolite imidazolate frameworks (ZIFs) materials as precursors for the preparation of electrocatalysts are characterized by self-doped nitrogen, high specific surface area, tunable composition, open pore structure, and chemical robustness. Transition metal atoms can be incorporated into N-C by pre-treatment or in situ treatment of ZIFs. Due to the strong component adaptability and structural tunability, ZIF-derived electrocatalysts can be designed and assembled to achieve the desired functionality. In this paper, the recent advances in ZIF-based materials for ZAB are reviewed from synthetic, structural, and compositional perspectives, and the catalytic mechanism is discussed. Finally, the challenges and opportunities of ZIFs-based materials and ZABs are envisioned. This paper paves the avenue for exploring efficient oxygen electrocatalysts and high-performance ZABs.