Atomic Fe-Zn dual-metal sites for high-efficiency pH-universal oxygen reduction catalysis

An effective electrocatalyst being highly active in all pH range for oxygen reduction reaction (ORR) is crucial for energy conversion and storage devices. However, most of the high-efficiency ORR catalysis was reported in alkaline conditions. Herein, we demonstrated the preparation of atomically dispersed Fe-Zn pairs anchored on porous N-doped carbon frameworks (Fe-Zn-SA/NC), which works efficiently as ORR catalyst in the whole pH range. It achieves high half-wave potentials of 0.78, 0.85 and 0.72 V in 0.1 M HClO4, 0.1 M KOH and 0.1 M phosphate buffer saline (PBS) solutions, respectively, as well as respectable stability. The performances are even comparable to Pt/C. Furthermore, when assembled into a Zn-air battery, the high power density of 167.2 mWcm(-2) and 120 h durability reveal the feasibility of Fe-Zn-SA/NC in real energy-related devices. Theoretical calculations demonstrate that the superior catalytic activity of Fe-Zn-SA/NC can be contributed to the lower energy barriers of ORR at the Fe-Zn-N-6 centers. This work demonstrates the potential of Fe-Zn pairs as alternatives to the Pt catalysts for efficient catalytic ORR and provides new insights of dual-atom catalysts for other energy conversion related catalytic reactions.

Automated summary

The study demonstrated the preparation of Fe-Zn-SA/NC catalyst for efficient ORR reaction in all pH range, showing high half-wave potentials and stability, comparable to Pt/C. The Fe-Zn-SA/NC catalyst also exhibited high power density and durability when assembled into a Zn-air battery, indicating its potential for real energy-related devices. The theoretical calculations attribute the superior catalytic activity of Fe-Zn-SA/NC to the lower energy barriers of ORR at the Fe-Zn-N-6 centers, offering new insights for dual-atom catalysts in energy conversion related catalytic reactions.