Phosphorus-Doped NiFe Electrodes for Stable Alkaline Seawater Electrolysis at Industrial Current Densities: Facile Synthesis and Mechanistic Insights

Direct seawater electrolysis offers a promising route for sustainable hydrogen production, particularly in offshore applications, yet challenges such as high overpotentials at industrial current densities and chloride-induced corrosion hinder its scalability. Herein, we report a phosphorus-doped NiFe electrode (P-NiFe-NF) synthesized via a scalable electrodeposition and vapor-phase deposition approach. The optimized P-NiFe-NF electrode achieves a low oxygen evolution reaction (OER) overpotential of 282 mV at 400 mA/cm² in simulated seawater and demonstrates exceptional stability for 175 hours under continuous operation at 400 mA/cm². The incorporation of phosphorus facilitates the in situ formation of a phosphate-rich surface layer, effectively repelling chloride ions and suppressing competitive chlorine evolution. Combined with the synergistic catalytic activity of Ni and Fe, this design enables high efficiency and durability at industrial-relevant current densities. The simplicity of the fabrication process and robust performance highlight its potential for large-scale hydrogen production from seawater.