Tailoring Fe–Nx electronic structure via Ce-based active oxygen inhibitor for enhanced oxygen reduction activity and stability

The development of highly active and durable oxygen reduction reaction (ORR) electrocatalysts is crucial for the advancement of zinc-air batteries. A dual-ligand stepwise preordination strategy is employed to synthesize the Fe–Ce bimetallic carbon-based catalyst (Ce/Fe–NC) with abundant Fe–N x /Ce–N x sites and Fe 3 O 4 , and a hierarchical micropore-mesopore structure. The introduction of Ce-related species significantly modulates the electronic structure of Fe sites, which is consistent with possible d–f orbital hybridization and d -band center regulation of Fe. Such electronic effect reduces the ORR energy barrier and endows Ce/Fe–NC with a half-wave potential of 0.875 V. The prepared CeO 2 with a fast Ce 3 + /Ce 4+ redox couple efficiently scavenges reactive oxygen species to inhibit the degradation of Fe–Nₓ sites and Fe 3 O 4 species, as well as the corrosion of carbon skeleton caused by Fenton reaction byproducts, ultimately enhancing the stability of the Ce/Fe–NC. After 30,000 accelerated cycles, the half-wave potential of the Ce/Fe–NC only decreases by 15 mV, and maintains a 95.4% current retention rate over 10,000 s. The zinc-air battery with Ce/Fe–NC achieves a peak power density of 230 mW cm −2 , a specific energy of 870.5 Wh kg –1 (Zn) , and a stable charge-discharge voltage gap over 100 h of cycling. This work provides a novel strategy for the preparation of high-performance non-precious metal ORR catalysts.