Preparation and application of rich nitrogen-doped porous Fe-N-C-based oxygen reduction catalysts

The highly active and stable oxygen reduction reaction (ORR) process is essential for driving the development of zinc-air batteries (ZABs). Therefore, by integrating the precise regulation of precursors, the tannic acid (TA) etching and nitrogen coordination strategy, a nitrogen-rich hierarchical porous Fe-N-C catalyst was successfully constructed. The uniform dispersion of particles was achieved by controlling the formation of the Fe-ZIF-8 precursor. Subsequent TA etching formed a rich mesoporous/microporous structure to improve active-site exposure. During the high-temperature pyrolysis process with melamine as the nitrogen source, a highly dispersed Fe-N X coordination structure was formed. Based on this rational design, the obtained catalyst presents a hierarchical porous structure, high nitrogen content and superior ORR activity, with a half-wave potential of 0.91 V in 0.1 M KOH solution. When applied to liquid and flexible ZABs, the catalyst delivers peak power densities of 186 mW cm −2 and 75 mW cm −2 , respectively, and cycling stability of over 1486 h is maintained in the liquid system-surpassing the performance of commercial Pt/C + RuO 2 . This research offers a fresh perspective on the design and synthesis of efficient ND-FeNC-TA catalysts and promotes the practical application of ZABs.