Heteroatom-Coordinated Fe–N ₄ Catalysts for Enhanced Oxygen Reduction in Alkaline Seawater Zinc-Air Batteries

A universal synthetic strategy was proposed to construct heteroatom axially coordinated Fe–N ₄ single-atom seawater catalyst materials (Cl–Fe–N ₄ and S–Fe–N ₄). The Cl–Fe–N ₄ 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–N ₄ demonstrates a power density of 187.7 mW cm ⁻² at 245.1 mA cm ⁻² and maintains stable cycling performance for 200 h.