Coupling of cerium oxide cyanamide with Fe–N–C for enhanced oxygen reduction reaction

Abstract

Iron–nitrogen-doped carbon (Fe–N–C) catalysts have been theoretically and experimentally demonstrated as one of the most promising materials to promote the oxygen reduction reaction (ORR), but they still have drawbacks in terms of stability and longevity. Herein, a novel strategy of loading Fe–N–C on cerium oxide cyanamide (Ce₂O₂CN₂) is proposed to increase the density of active sites and improve the activity effectively. Ce₂O₂CN₂ provides a Ce⁴⁺/Ce³⁺ redox pair to regulate the oxygen density on the catalyst surface, and the π–π interactions between Ce₂O₂CN₂ and Fe–N–C are beneficial for interfacial charge transport. Consequently, Fe–N–C@Ce₂O₂CN₂ shows excellent ORR activity with a half-wave potential (E_1/2) of 0.89 V vs RHE and satisfactory long-term durability in an alkaline medium, and significantly outperforms commercial Pt/C. The Zn–air batteries made using the prepared catalyst exhibited a high peak power density of 119.35 mW cm⁻². This study provides a new perspective for the application of platinum group-metal (PGM)-free catalysts in next-generation energy storage devices.