Ni-P Nanoarray Scaffolds That Elevate Self-Supported Phosphides and Commercial Catalysts for Alkaline and...

Alkaline water electrolysis offers a cost-effective and robust route to green hydrogen production, but its practical deployment is hindered by sluggish hydrogen evolution reaction (HER) kinetics and electrode degradation. Herein, we report a self-supported hierarchical Co₃Mo₁-P/Ni-P/NF (NF: nickel foam) electrode fabricated by a two-step molten-salt method. Vertically aligned Ni-P nanoneedles are grown directly on NF, followed by deposition of a Co₃Mo₁-P catalytic overlayer. The resulting electrode requires only 45.9 mV at 10 mA cm^-2 and delivers outstanding high-current alkaline HER performance, outperforming previously reported transition-metal phosphide electrodes. This activity arises from synergistic Co-Mo chemistry, beneficial Ni-P/catalyst interfacial effects, and engineered surface topography that accelerates bubble release while maximizing active-site exposure. The Ni-P scaffold further enhances physical and chemical robustness, enabling stable water splitting for 200 h. Moreover, integrating commercial Pt/C with the Ni-P nanoarray increases the electrochemically active surface area by 4.52-fold and achieves 55.8 mV at 100 mA cm^-2, demonstrating the versatility of the scaffold. Single-cell anion-exchange membrane water electrolysis (AEMWE) further confirms that this hierarchical phosphide architecture translates intrinsic catalytic advantages into superior cell-level performance under practical membrane-electrode assembly conditions.