Charge Redistribution via d-p Hybridization in NiCoP Supported on Ni₅P₄ Boosts Alkaline Hydrogen Production

Transition-metal phosphides (TMPs) are promising electrocatalysts for the hydrogen evolution reaction (HER), but their industrial-scale application is limited by sluggish water dissociation kinetics and insufficient active site exposure under alkaline conditions. Herein, we demonstrate orbital hybridization engineering in Ni₅P₄/NiCoP-1 heterostructures fabricated via controlled phosphorization and magnetically modulated electrodeposition (MME). COMSOL simulations, X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations reveal that the heterointerface activates covalent Ni/Co-P bonding through optimized d-p orbital hybridization, leading to favorable electron density redistribution and an upshifted d-band center (ΔE = 0.061 eV). These electronic modifications synergistically enhance OH^- adsorption energetics and accelerate water dissociation kinetics. Simultaneously, the strengthened metal-phosphorus bonds endow exceptional corrosion resistance under chloride-rich seawater conditions. As a result, Ni₅P₄/NiCoP-1 achieves excellent HER performance, requiring ultralow overpotentials of 266 and 325 mV to achieve a current density of 1000 mA cm^-2 in 1.0 M KOH and seawater at pH 14, respectively, while maintaining stable operation for 200 h. In a two-electrode electrolyzer, the system requires only 1.62 V to reach 100 mA cm^-2 in urea-assisted alkaline seawater, surpassing most reported TMP-based catalysts. The practical applicability is further verified by successfully powering a hydrogen-powered prototype vehicle. This work not only provides mechanistic insights into interfacial electronic structure modulation via d-p orbital hybridization but also establishes MME as a universal approach for high-rate hydrogen production from alkaline freshwater and seawater.