Rational Design of Self-Supported Ni3Fe–Ni3P/NF Electrocatalyst for pH-Universal Hydrogen Evolution Reaction

The development of Ni–P-based electrocatalysts with high active site density and superior intrinsic activity remains challenging in achieving an efficient and durable hydrogen evolution reaction (HER). Herein, we report a heterostructure catalyst prepared by electroless plating on nickel foam (NF) followed by a temperature-programmed hydrogen reduction. The prepared Ni₃Fe–Ni₃P/NF catalyst achieves remarkably low overpotentials of 61, 108, and 91 mV at −10 mA cm^–2 in acidic (0.5 M H₂SO₄), alkaline (1.0 M KOH), and neutral (1.0 M PBS) electrolytes, respectively. It is revealed that a mutually enhanced synergistic effect between Ni₃Fe intermetallic compounds and Ni₃P phosphides concertedly boosts the HER kinetics. The electroless plating step is found to be essential for constructing a continuous smooth interfacial layer, effectively expanding the three-dimensional architecture of the catalyst while optimizing its electronic structure.