Interfacial Charge Transfer in a Hierarchical Ni₂P/FeOOH Heterojunction Facilitates Electrocatalytic Oxygen Evolution

The construction of a heterojunction is an important strategy to develop efficient electrocatalysts. However, the precise design and preparation of the heterojunction with desirable catalytic performance remain a challenge. Herein, a hierarchical Ni₂P/FeOOH Schottky junction supported on nickel foam was prepared by electrodeposition of FeOOH on the surface of Ni₂P. The electrocatalytic activity of the Ni₂P/FeOOH Schottky junction can be remarkably improved, owing to the unique hierarchical architecture and strong electron interaction in the Ni₂P/FeOOH Schottky junction. As-prepared Ni₂P/FeOOH exhibits excellent electrocatalytic activity for an oxygen evolution reaction (OER) with an ultralow overpotential of 246 mV to reach 100 mA cm^-2 and a small Tafel slope of 62.8 mV dec^-1. This work provides not only a new method for the design of hierarchical nanomaterials but also an efficient strategy to design efficient OER electrocatalysts by constructing hierarchical heterojunctions.