Structural reconfiguration of an Ru-bearing high-entropy sulfide into an efficient alkaline oxygen evolution catalyst

High-entropy sulfides (HESs) with multiple metals are one of the most promising electrocatalysts, but the ambiguous self-reconstruction mechanism greatly hinders their further practical applications in water electrolysis. Here, an Ru-bearing high-entropy sulfide (FeCoNiCuRu)S₂ was prepared by employing a facile high-pressure and high-temperature (HPHT) method. The obtained high-entropy sulfide (FeCoNiCuRu)S₂ exhibited excellent OER performance and robust stability in a 1 M KOH solution. By employing operando X-ray absorption spectroscopy (XAS) and Raman spectroscopy, along with ex situ TEM and XPS characterization, we determine the specific self-reconstruction path (MS₂ was directly converted into MOOH) and real active species. This research offers great opportunities for the development of highly efficient catalysts.