Adsorbate- and Dopant-Engineered Active Nanostructure Derived from Ordered Er-Ni-B Intermetallics Boosts Alkaline Oxygen Evolution

The oxygen evolution reaction (OER) remains the efficiency bottleneck of alkaline water electrolysis for carbon-neutral hydrogen. Herein, we propose a synergy strategy that couples p−d−f block elements within an intermetallic phase to deploy an ordered ternary ErNi4B alloy, which functions as a self-reconstructing precatalyst for the OER. Operando Raman, differential electrochemical mass spectrometry (DEMS), depth-resolved X-ray photoelectron spectroscopy (XPS), and density-functional theory (DFT) uncover that in situ conversion from ErNi4B to Er-doped NiOOH adsorbed with borate ions during the OER yields an active shell operating via the adsorbate-evolution mechanism, while the metallic core preserves high conductivity, cooperatively optimizing the adsorption free energy of intermediates and suppressing the leaching of active Ni species. Benefiting from these aspects, the precatalyst demands only 338 mV to deliver 500 mA cm−2 and sustains industrial current density higher than 600 mA cm−2 for 1000 h. Meanwhile, it also showed high potential as an anode for anion exchange membrane water electrolysis. These findings redefine the shell-active/bulk-conductive paradigm and offer a general stoichiometric-phase roadmap to design ultrastable and non-precious OER precatalysts toward carbon-neutral hydrogen.