Immobilizing Low-Cost Metal Nitrides in Electrochemically Reconstructed Platinum Group Metal (PGM)-Free Oxy-(Hydroxides) Surface for Exceptional OER Kinetics in Anion Exchange Membrane Water Electrolysis

A highly efficient and platinum group metal (PGM)-free oxygen evolution reaction (OER) electrode is developed by immobilizing Ni₃N particles on the electrochemically reconstructed amorphous oxy-hydroxides surface, resulting in a twofold higher industrial relevance current density of 1 A cm_geo⁻² at an ultra-small overpotential η(O₂) of 271 mV, with a high turnover frequency of 2.53 s⁻¹, high Faradic efficiency of 99.6 % and exceptional OER stability of 1000 h in continuous electrolysis. Such a unique amorphous-crystalline interface with enriched active sites greatly facilitates electron transport and OER kinetics at the electrode-electrolyte interface. Further, combined with an efficient PGM-free cathode (MoNi₄/MoO₂@Ni), this electrode demonstrates a current density of 685 mA cm_geo⁻² at 1.85 V_cell at 70 °C in an anion exchange membrane water electrolyzer (AEMWE) operated with ultra-pure water-electrolyte. These findings highlight the design of highly-efficient oxygen-evolving catalysts and significant advancement in the practical implementation of AEMWEs for grid-scale hydrogen production.