Key Takeaways & Executive Findings
- •• 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). • 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%). • 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. • Density functional theory calculations revealed that axial heteroatom coordination regulates the electron center of Fe single atoms, enhancing ORR activity and Cl− poisoning resistance.
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.
1. Introduction
Seawater zinc-air batteries (SZABs) have emerged as a promising energy storage technology due to their high energy density, environmental sustainability, and direct utilization of abundant seawater as electrolyte [1–3]. Unlike conventional batteries, SZABs uses seawater as electrolyte due to its high ionic conductivity of seawater rather, avoiding the need of fresh water resources and enabling cost-effective and scalable applications in marine [4–6]. One of the key issues which limit the overall efficiency and energy output of SZAB is the sluggish oxygen reduction reaction (ORR) [7–9]. The inherently slow kinetics due to the 4-electron transfer process requires high-performance electrocatalysts to accelerate reaction rates and reduce overpotentials [10]. Although noble metal-based electrocatalysts such as Pt exhibit excellent catalytic performance [11–14], their high costs limit the practical applications in energy-related devices [15, 16]. Moreover, another major challenge to metal-based catalyst in seawater environment is the poor stability due to the presence of high concentration of Cl−, which can easily adsorb onto metal center, resulting in a decrease in catalytic active site and even shifting the ORR pathway from the preferred four-electron reduction of O2 to H2O toward an unfavorable two-electron reduction to H2O2 [17–19]. Additionally, Cl−-induced corrosion and the formation of inactive metal-chloride (M-Cl) species further exacerbate performance degradation [20]. To address these challenges, extensive research has been focused on the development of electrocatalysts which not only enhance ORR activity but also exhibit strong resistance to Cl− poisoning and side reactions.
Single-atom catalysts (SACs) have attracted significant attention due to their maximized atomic utilization efficiency, well-defined active sites, and tunable electronic structures [21]. Their atomically dispersed metal centers also minimize aggregation and enhance stability under various electrochemical conditions [22]. Recent studies have demonstrated that Fe-based SACs showed comparable performance as Pt-based catalysts in alkaline ORR, sometime even better, particularly when their coordination environments are optimized [23–25]. Current strategies focus on modifying the electronic structure of active sites or engineering protective layer around active sites to mitigate undesired interaction
Loading authentic research manuscript (Pages 1–5)...
Wenhan Fang, Kailong Xu, Xinlei Wang, Yuanhang Zhu, Xiuting Li, Hui Liu, Danlei Li, Jun Wu (2026). Heteroatom-Coordinated Fe–N4 Catalysts for Enhanced Oxygen Reduction in Alkaline Seawater Zinc-Air Batteries. Nano-Micro Letters. https://doi.org/10.1007/s40820-025-01943-6
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the main innovation of this study?
The study proposes a universal synthetic strategy to construct heteroatom axially coordinated Fe–N4 single-atom catalysts (Cl–Fe–N4 and S–Fe–N4) for enhanced oxygen reduction in alkaline seawater zinc-air batteries, with Cl–Fe–N4 showing superior performance and Cl− poisoning resistance.
How does Cl–Fe–N4 compare to commercial Pt/C in ORR activity?
Cl–Fe–N4 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%).
What is the significance of the seawater-based zinc-air battery performance?
The 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, indicating practical applicability.
What role does density functional theory (DFT) play in this research?
DFT calculations revealed that axial heteroatom coordination regulates the electron center of Fe single atoms, leading to more active reaction intermediates and increased electron density, thereby enhancing ORR activity.
Why is Cl− poisoning resistance important for seawater catalysts?
In seawater, high Cl− concentration can adsorb onto metal centers, reducing active sites and shifting ORR to unfavorable two-electron pathway. Cl–Fe–N4 shows stronger Cl− poisoning resistance, enhancing stability and performance.
Related Technical Papers & Translations
Direct Repair of the Crystal Structure and Coating Surface of Spent LiFePO4 Materials Enables Superfast Li-Ion Migration
The rapid accumulation of spent LiFePO4 (LFP) cathodes from retired lithium-ion batteries necessitates the development of effective and environmental-friendly recycling strategies. In this context, direct regeneration has emerged as a promising approach for reclaiming LFP cathode materials, offering a streamlined pathway to restore their electrochemical functionality. We report an integrated regeneration protocol that simultaneously repairs the degraded crystal structure and reconstructs the damaged carbon coating in spent LFP. The regenerated cathode material had superfast lithium-ion diffusion kinetics and a stable cathode–electrolyte interface, giving a remarkable rate capability with specific capacities of 122 mAh g−1 at 5C and 106 mAh g−1 at 10C (1C = 170 mA g−1). It also maintained capacities of 110.7 mAh g−1 (5C) and 84.1 mAh g−1 (10C) after 400 cycles. It could be used in harsh environments and could be stably cycled at subzero temperatures (−10 and −20 °C) and in solid-state electrolyte batteries. Life cycle assessment combined with economic evaluation using the EverBatt model reveals that this direct regeneration approach has high economic and environmental benefits.
Oxide Semiconductor for Advanced Memory Architectures: Atomic Layer Deposition, Key Requirement and Challenges
Oxide semiconductors (OSs), introduced by the Hosono group in the early 2000s, have evolved from display backplane materials to promising candidates for advanced memory and logic devices. The exceptionally low leakage current of OSs and compatibility with three-dimensional (3D) architectures have recently sparked renewed interest in their use in semiconductor applications. This review begins by exploring the unique material properties of OSs, which fundamentally originate from their distinct electronic band structure. Subsequently, we focus on atomic layer deposition (ALD), a core technique for growing excellent OS films, covering both basic and advanced processes compatible with 3D scaling. The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced. Furthermore, material design strategies, such as cation selection, crystallinity control, anion doping, and heterostructure engineering, are discussed. We also highlight challenges in memory applications, including contact resistance, hydrogen instability, and lack of p-type materials, and discuss the feasibility of ALD-grown OSs as potential solutions. Lastly, we provide an outlook on the role of ALD-grown OSs in memory technologies. This review bridges material fundamentals and device-level requirements, offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
Laser powder bed fusion of biodegradable Zn-4Cu alloy: Processing, microstructure and properties
Zn's natural degradability and biocompatibility make it a promising candidate for implants, however, its mechanical properties remain insufficient for bone applications. In this study, the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion (LPBF). Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed. Under optimized conditions of 100 W and 100 mm/s, high-density (99.58%) Zn-Cu alloys with improved hardness (68.2HV) and yield strength (160 MPa) were achieved. These improvements are attributed to solid solution strengthening, segregation strengthening, and grain refinement. The Zn-Cu alloys also demonstrated favorable degradation behavior, with a rate of 0.16 mm/year. This degradation is primarily driven by micro-galvanic corrosion between the CuZn5 phase and Zn matrix, along with refined grains and increased grain boundary density. This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.