Narrowing High-Valent Ni Formation Potential and Widening Urea Oxidation Window by Ni₂P/MoP Hybrid Catalyst

Achieving selective and energy-efficient urea oxidation is a key challenge in urea-assisted water electrolysis due to sluggish activation of nickel sites and their limited active potential range. Here, we construct Ni₂P/MoP embedded in conductive carbon nanofibers (Ni₂P/MoP/CNFs) that couple precise interfacial charge redistribution with synergistic electronic modulation to accelerate high-valent Ni³⁺ sites formation (50 vs. 140 mV of Ni₂P) and expand urea oxidation potential window (290 vs. 150 mV of Ni₂P). Electronic coupling shifts the Ni d-band center, promoting rapid Ni²⁺/Ni³⁺ transformation and optimizing intermediate adsorption–desorption. In situ Raman and FTIR analyses identify NiOOH as the active phase that facilitates early-stage C─N bond cleavage and suppresses oxygen evolution up to 110 mV beyond its onset in the pure Ni₂P system. Supported by density functional theory calculations, this interfacial modulation reduces the energy barrier for urea oxidation from 1.84 to 1.76 eV. Benefiting from this unique electronic structure, Ni₂P/MoP/CNFs achieve a current density of 141.2 mA cm⁻² at 1.54 V, 2.9 times that of the Ni₂P/CNFs; and it also shows good stability in the urea electrolysis for hydrogen generation over 100 h. This work advances efficient hydrogen production via urea electrolysis by bridging Ni activation kinetics and oxidation selectivity.