Structural and Interfacial Engineering of Ni₂P/Fe₃O₄ Porous Nanosheet Arrays for Efficient Oxygen Evolution Reaction

Rational design of transition-metal phosphide (TMPs)-based electrocatalysts can effectively promote oxygen evolution reaction (OER). Herein, the novel efficient Ni₂P/Fe₃O₄ porous nanosheets arrays supported on Ni foam (Ni₂P/Fe₃O₄/NF) as alkaline OER catalysts were synthesized using structural and interfacial engineering. The three-dimensional (3D) porous hierarchical structure of Ni₂P/Fe₃O₄/NF provides abundant active sites for OER and facilitates the electrolyte diffusion of ions and O₂ liberation. Furthermore, the strong interfacial coupling and synergistic effect between Ni₂P and Fe₃O₄ modify the electronic structure, resulting in the enhanced intrinsic activity. Consequently, the optimized Ni₂P/Fe₃O₄/NF exhibits excellent OER performance with low overpotentials of 213 and 240 mV at 60 and 100 mA cm^-2 in 1.0 M KOH, respectively, better than the RuO₂/NF and most Ni/Fe-based OER catalysts. Impressively, it can maintain its catalytic activity for at least 20 h at 60 mA cm^-2. In addition, the relationship between the structure and performance is fully elucidated by the experimental characterizations, indicating that the metal oxyhydroxides in situ generated on the surface of catalysts are responsible for the high OER activity.