Fe-N-C catalysts decorated with oxygen vacancies-rich CeO_x to increase oxygen reduction performance for Zn-air batteries

Platinum group metal (PGM)-free catalysts represented by nitrogen and iron co-doped carbon (Fe-N-C) catalysts are desirable and critical for metal-air batteries, but challenges still exist in performance and stability. Here, cerium oxides (CeO_x) are incorporated into a two-dimensional Fe-N-C catalyst (FeNC-Ce-950) via a host-guest strategy. The Ce⁴⁺/Ce³⁺ redox system creates a large number of oxygen vacancies for rapid O₂ adsorption to accelerate the kinetics of oxygen reduction reaction (ORR). Consequently, the as-synthesized FeNC-Ce-950 catalyst exhibits a half-wave potential (E_1/2) of 0.921 V and negligible decay (<2 mV for ΔE_1/2) after 5,000 accelerated durability cycles, significantly outperforming most of ORR catalysts reported in recent years and precious metal counterparts. When applied in a zinc-air battery, it demonstrates a peak power density of 175 mW cm⁻² and a specific capacity of 757 mAh g_Zn⁻¹. This study also provides a reference for the exploration of Fe-N-C catalysts decorated with variable valence metal oxides.