Self-Supported FeNi‑P Nanosheets with Thin Amorphous Layers for Efficient Electrocatalytic Water Splitting

Low-cost and efficient catalytic electrode toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is strongly attractive for overall water splitting. Herein, a 3D bifunctional electrode of FeNi phosphide nanosheets with a thin amorphous layer on Nickel foam (FeNi-P/NF) is designed via phosphorizing NiFe-layered double hydroxide-coated nickel foam (FeNi LDH/NF) in red phosphorus vapor at 500 °C. Benefiting from the unique architecture with increased exposure and accessibility of active sites, the electrode exhibits excellent electrocatalytic performance toward both HER and OER in 1.0 M NaOH with 102 and 224 mV low overpotentials to achieve a catalytic current density of 10 mA cm^–2, respectively. As a bifunctional electrode, the FeNi-P/NF can release a current density of 10 mA cm^–2 at a low cell voltage of 1.57 V and 100 mA cm^–2 at 1.82 V in an alkali electrolyzer, possessing significant durability over 100 h electrolysis at high current density of 100 mA cm<sup>–2