Interface-Engineered Ni(OH)₂/β-like FeOOH Electrocatalysts for Highly Efficient and Stable Oxygen Evolution Reaction

Iron-based (oxy)hydroxides are especially attractive electrocatalysts for the oxygen evolution reaction (OER) owing to their earth abundance, low cost, and nontoxicity. However, poor OER kinetics on the surface restricts the performance of the FeOOH electrocatalyst. Herein, a highly efficient and stable Ni(OH)₂/β-like FeOOH electrocatalyst is obtained by facile electroactivation treatment. The activated Ni(OH)₂/β-like FeOOH sample indicates an overpotential of 300 mV at 10 mA cm⁻² for the OER, and no clear current decay after 50 h of testing; this is comparable to the most efficient nickel- and cobalt-based electrocatalysts on planar substrates. Furthermore, studies suggest that β-like FeOOH plays a key role in remarkably enhancing the performance during the electroactivation process owing to its metastable tunnel structure with a lower barrier for interface diffusion of Ni²⁺ ions between the bilayer electrocatalyst. This study develops a new strategy to explore efficient and low-cost electrocatalysts and deepens understanding of bilayer electrocatalysts for the OER.