In Situ Construction of FeNi 3 ‐Embedded Hf‐Ni 2 P‐Fe 2 P/Nickel Foam Nanosheets for Boosted Electrocatalyst Overall Water Splitting

Vertically interlaced metal phosphides nanosheets filled with alloy nanoparticles Hf-Ni₂P-Fe₂P-FeNi₃/nickel foam (Hf-MP-MA/NF) have been produced by solvothermal and hypophosphite pyrolysis techniques that exhibit extreme electrical conductivity, high electrochemical efficiency, and astonishing stability. The Hf-MP-MA/NF exhibits excellent trifunctional electrocatalytic activity for hydrogen evolution (η₁₀ = 83 mV), oxygen evolution (η₁₀ = 218 mV), and urea oxidation reaction (E₁₀ = 1.34 V). Meanwhile, only 1.52 V is needed for Hf-MP-MA/NF_{(+, -)} at 10 mA cm^-2 to drive overall water splitting, and the stability can be maintained at 94.5% after 100 h of continuous operation in alkaline solution. Furthermore, its stability can be only maintained at 74.9% when operated continuously in an alkaline solution for 35 h at 100 mA cm^-2. The outstanding electrocatalytic performance of the Hf-MP-MA/NF catalyst is fundamentally determined by the synergistic effect of the alloy and metal phosphides, enhancing the utilization of active sites, improving electron conductivity, and optimizing reaction kinetics, all of which contribute to its remarkable efficiency and stability in electrochemical processes. It is anticipated that the preparation strategy of multiphase compounds can be generalized to electrochemical applications involving hydrogen.