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Vol. 18 (2026)

Heteroatom-Coordinated Fe–N4 Catalysts for Enhanced Oxygen Reduction in Alkaline Seawater Zinc-Air Batteries

https://doi.org/10.1007/s40820-025-01943-6
Wenhan Fang
Department of Chemistry and Materials Science, School of Science, Xi’an Jiaotong-Liverpool University, Suzhou 215123, People’s Republic of China
Kailong Xu
Department of School of Metallurgy and Environment, Central South University, Changsha 410083, People’s Republic of China
Xinlei Wang
Department of School of Metallurgy and Environment, Central South University, Changsha 410083, People’s Republic of China
Yuanhang Zhu
Institute for Advanced Study, Shenzhen University, Shenzhen 518060, People’s Republic of China
Xiuting Li
Institute for Advanced Study, Shenzhen University, Shenzhen 518060, People’s Republic of China
Hui Liu
Department of School of Metallurgy and Environment, Central South University, Changsha 410083, People’s Republic of China
Danlei Li
Department of Chemistry and Materials Science, School of Science, Xi’an Jiaotong-Liverpool University, Suzhou 215123, People’s Republic of China
Jun Wu
Department of School of Metallurgy and Environment, Central South University, Changsha 410083, People’s Republic of China

Corresponding Author: Danlei Li

danlei.li@xjtlu.edu.cn

Nano-Micro Letters, Vol. 18 (2026), Article Number: 96

Abstract

Seawater zinc-air batteries are promising energy storage devices due to their high energy density and utilization of seawater electrolytes. However, their efficiency is hindered by the sluggish oxygen reduction reaction (ORR) and chloride-induced degradation over conventional catalysts. In this study, we proposed a universal synthetic strategy to construct heteroatom axially coordinated Fe–N4 single-atom seawater catalyst materials (Cl–Fe–N4 and S–Fe–N4). X-ray absorption spectroscopy confirmed their five-coordinated square pyramidal structure. Systematic evaluation of catalytic activities revealed that compared with S–Fe–N4, Cl–Fe–N4 exhibits smaller electrochemical active surface area and specific surface area, yet demonstrates higher limiting current density (5.8 mA cm−2). The assembled zinc-air batteries using Cl–Fe–N4 showed superior power density (187.7 mW cm−2 at 245.1 mA cm−2), indicating that Cl axial coordination more effectively enhances the intrinsic ORR activity. Moreover, Cl–Fe–N4 demonstrates stronger Cl− poisoning resistance in seawater environments. Chronoamperometry tests and zinc-air battery cycling performance evaluations confirmed its enhanced stability. Density functional theory calculations revealed that the introduction of heteroatoms in the axial direction regulates the electron center of Fe single atom, leading to more active reaction intermediates and increased electron density of Fe single sites, thereby enhancing the reduction in adsorbed intermediates and hence the overall ORR catalytic activity.


Highlights:
1 A universal synthetic strategy was proposed to construct heteroatom axially coordinated Fe–N4 single-atom seawater catalyst materials (Cl–Fe–N4 and S–Fe–N4).
2 The Cl–Fe–N4 catalyst achieves a limiting current density of 5.8 mA cm−2 and a half-wave potential of 0.931 V vs. RHE in alkaline synthetic seawater, outperforming commercial Pt/C (40 wt%).
3 The seawater-based zinc-air battery fabricated with Cl–Fe–N4 demonstrates a power density of 187.7 mW cm−2 at 245.1 mA cm−2 and maintains stable cycling performance for 200 h.

Keywords

Single-atom catalyst Zinc-air battery Seawater catalyst Oxygen reduction reaction
Fang, Wenhan, Kailong Xu, Xinlei Wang, Yuanhang Zhu, Xiuting Li, Hui Liu, Danlei Li, and Jun Wu. 2026. “Heteroatom-Coordinated Fe–N4 Catalysts for Enhanced Oxygen Reduction in Alkaline Seawater Zinc-Air Batteries”. Nano-Micro Letters 18 (January):96. https://doi.org/10.1007/s40820-025-01943-6.
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