Bio-inspired Design of Hierarchically Porous ZIF-8 derived Fe-N-C Bifunctional Catalysts for Enhanced Zinc-Air Battery Performance

Zeolitic Imidazolate Frameworks (ZIF-8) has emerged as promising candidate for alleviating the aggregation of Fe 3 N-catalysts, exhibiting significantly improved oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for rechargeable zinc-air batteries. To further improve the catalytic performance, it is crucial to fabricate ZIF-8 with hierarchically porous structures, which remains challenging due to the rapid crystallization kinetics and the weak interactions. Inspired by biological porous materials, we developed a novel method using 1,3,5-trimethylbenzene TMB as a mediating molecule to dynamically regulate the organic-inorganic interface between templates and ZIF-8 precursors, achieving the micro-meso-macropores of ZIF-8, which synergistically enhances mass transport and active site accessibility. Additionally, TMB preserves the weakly alkaline environment required for ZIFs’ structural integrity by leveraging its hydrophobic co-solvent effect. The as-synthesized Fe 3 N-HPZIF-8 catalyst integrates Fe 3 N active sites, hierarchically porous structures, and pyrrolic-N dopants, resulting in the exceptional bifunctional activity in alkaline media (ΔE = 0.619 V), exceeding most benchmark catalysts. When integrated into zinc-air batteries, a peak power density of 205.2 mW cm -2 is achieved. This work presents a generalizable synthetic approach for high-performance metal-air battery catalysts.