Phosphorization-pyrolysis engineered FeP@CNT heterostructures for efficient and durable direct seawater electrolysis

초록

Direct seawater electrolysis offers a sustainable pathway for hydrogen (H2) production but is hindered by sluggish kinetics and severe chloride-induced corrosion. Here, we report a Phosphorization-Pyrolysis (PhosPy) strategy to construct a CNT-confined FeP heterostructure derived from a ZnFe metal-organic framework (MOF). During the PhosPy transformation, MOF-derived Fe species catalyze in situ CNT growth while simultaneously forming FeP, creating a strongly coupled FeP@CNT architecture with enhanced conductivity and structural stability. As a result, FeP@CNT-900 exhibits excellent bifunctional electrocatalytic activity in natural seawater, requiring only 74 mV for HER and 184 mV for OER to reach 10 mA cm-2. A symmetric electrolyzer delivers 100 mA cm-2 at 1.49 V, outperforming the benchmark Pt/C RuO2 system, and maintains stable operation for over 1000 h at 500 mA cm-2 under practical conditions. Mechanistic analysis reveals a synergistic chloride-tolerant interface, where FeP preferentially adsorbs OH-while the CNT scaffold restricts Cl-diffusion. These findings establish a new catalyst design template integrating MOF-derived phosphide engineering, self-catalyzed CNT confinement, and interfacial ion regulation for efficient and durable H2 production directly from seawater.

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