A Strongly Coupled Pt-W2N Heterostructure Embedded in Porous Carbon Nanoflowers for Seawater Electrolysis

• • Overpotentials of 1.2, 7, and 32.2 mV at 10 mA cm−2 in acidic, neutral, and alkaline electrolytes, respectively, significantly lower than commercial 20 wt% Pt/C, enabling high-efficiency hydrogen production across diverse pH conditions. • • In alkaline seawater, the catalyst achieves an ultra-low HER overpotential of 163.8 mV at 700 mA cm−2, demonstrating exceptional performance at industrially relevant current densities and superior chloride tolerance (0.5–2.5 M NaCl). • • A practical seawater electrolyzer (Pt-W2N@C||NiFe-LDH) requires only 1.992 V to drive 500 mA cm−2, maintaining 95.8% activity retention over 80 h of continuous operation, indicating robust durability for large-scale deployment. • • The strong coupling between Pt and W2N at the heterointerface optimizes H* and OH* adsorption and enhances water dissociation kinetics, as confirmed by in situ Raman spectroscopy, providing a design strategy for low-Pt-loading catalysts that balance cost and performance.