Accelerating the Transformation of Active β-NiOOH on NiFe Layered Double Hydroxide via Cation–anion Collaborative Coordination for Alkaline Water Oxidation at High Current Densities

Abstract

The NiFe-based layered double hydroxides (LDH) undergo surface reconstruction, generating metal hydroxyl oxides that act as active species during the alkaline oxygen evolution reaction (OER). However, the sluggish reconstruction process and excessive oxidation at higher anodic potentials frustrate the alkaline OER activity and stability. Herein, a cation–anion collaborative coordination strategy is harnessed to build (Ni, Fe)─S─Zn coordination structures in NiFe LDH on the nickel foam (S-NiFeZn LDH/NF), which lowers the reconstruction energy barrier and aids in forming highly active β-NiOOH during the alkaline OER process. Meanwhile, the coordination structures also optimize the adsorption of oxygen-containing intermediates, enhancing OER kinetics. As a result, S-NiFeZn LDH/NF achieves low overpotentials of 201 mV at 10 mA cm⁻² and 293 mV at 500 mA cm⁻² in 1.0 m KOH. Moreover, the cell assembled with S-NiFeZn LDH/NF as the anode and commercial NiMo foam as the cathode demonstrates excellent overall water splitting activity, with voltages of 1.62 and 1.81 V at 10 and 500 mA cm⁻² in 1.0 m KOH, and exhibits ultralong-term durability over 500 h at 500 mA cm⁻², even operating stably for 200 h in an alkaline water electrolyzer under industrial conditions (30% KOH at 80 °C).