Constructing Dendritic High Entropy Sulfide for Boosting Water Electrolysis

ABSTRACT High entropy sulfides (HESs) stand out as prospective electrocatalysts for water hydrolysis due to their singular structure and electronic properties. However, compared with other high entropy materials, HESs remain largely unexplored owing to the challenge in achieving robust electrodes with high performance. Herein, we fabricate (FeCoNiCrCu) 3 S 2 HES on nickel foam (NF) via an ion‐exchange strategy under mild solvothermal conditions, working as robust bifunctional water electrolysis electrodes. The different solubility products of sulfides render it a dendritic architecture with abundant sulfur vacancies, which facilitates mass transport and active sites exposure and endows its higher hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity and stability, compared with ternary and quarternary alternatives. It demands only 1.719 V to reach 100 mA cm −2 for overall water splitting and sustains 0.5 A cm −2 for 110 h, while equipped in customized anion exchange membrane water electrolyzer (AEMWE). In situ Raman and XPS analysis substantiated the reconstructed active sites and demonstrates the controlled formation of sulfate in electrolyte, contributing to the enhanced HER and OER performance. The work provides a scalable route to low‐cost, phase pure HES electrocatalysts and advances sustainable water electrolysis.