Unveiling the Synergistic Effect of Two-Dimensional Heterostructure NiFeP@FeOOH as Stable Electrocatalyst for Oxygen Evolution Reaction

Introducing multiple active sites and constructing a heterostructure are efficient strategies to develop high-performance electrocatalysts. Herein, two-dimensional heterostructure NiFeP@FeOOH nanosheets supported by nickel foam (NF) are prepared by a hydrothermal–phosphorization–electrodeposition process. The synthesis of self-supporting heterostructure NiFeP@FeOOH nanosheets on NF increases the specific surface region, while bimetallic phosphide realizes rapid charge transfer, improving the electron transfer rate. The introduction of FeOOH and the construction of a heterostructure result in a synergistic effect among the components, and the surface-active sites are abundant. In situ Raman spectroscopy showed that the excellent oxygen evolution reaction (OER) performance was due to reconstruction-induced hydroxyl oxide, which achieved a multi-active site reaction. The NiFeP@FeOOH/NF electrocatalytic activity was then significantly improved. The findings indicate that in a 1.0 M KOH alkaline solution, NiFeP@FeOOH/NF showed an OER overpotential of 235 mV at 100 mA cm−2, a Tafel slope of 46.46 mV dec−1, and it worked stably at 50 mA cm−2 for 80 h. This research proves that constructing heterostructure and introducing FeOOH are of great significance to the study of the properties of OER electrocatalysts.