Heteroatom anchors Fe-Mn dual-atom catalysts with bi-functional oxygen catalytic activity for low-temperature rechargeable flexible Zn-air batteries

Abstract

M−N−C (M = Fe, Co, Ni, etc.) catalyst owns high catalytic activity in the oxygen catalytic reaction which is the most likely to replace the Pt-based catalysts. But it is still a challenge to further increase the active site density. This article constructs the high-efficiency FeMn-N/S-C-1000 catalyst to realize ORR/OER bifunctional catalysis by hetero-atom, bimetal (Fe, Mn) doped simultaneously strategy. When evaluated it as bi-functional electro-catalysts, FeMn-N/S-C-1000 exhibits excellent catalytic activity (E1/2 = 0.924 V, Ej=10 = 1.617 V) in alkaline media, outperforms conventional Pt/C, RuO2 and most non-precious-metal catalysts reported recently. Such outstanding performance is owing to N, S co-coordinated with metal to form multi-types of single atom, dual atom active sites to carry out bi-catalysis. Importantly, nitrite poison test provides the proof that the active sites of FeMn-N/S-C are more than that of single-atom catalysts to promote catalytic reactions directly. To better understand the local structure of Fe and Mn active sites, XAS and DFT were employed to reveal that FeMn-N5/S-C site plays the key role during catalysis. Notably, the FeMn-N/S-C-1000 based low-temperature rechargeable flexible Zn-air also exhibits superior discharge performance and extraordinary durability at −40 °C. This work will provide a new idea to design diatomic catalysts applied in low-temperature rechargeable batteries.