Single‐Atom Sb‐Doped RuSbO_x Bifunctional Catalysts for Ultra‐Stable PEM Water Electrolyzers

Developing highly efficient and stable Pt/Ir-free bifunctional catalysts is very urgent for lowering the catalyst cost of proton exchange membrane water electrolyzer (PEMWE). Herein, a single-atom Sb-doped RuSbO_x bifunctional catalyst is developed for ultra-stable PEMWE. RuSbO_x exhibits excellent stability with a long-term operation of 150 h for oxygen evolution reaction (OER) and 300 h for hydrogen evolution reaction (HER) at 100 mA cm^-2 in acidic media, respectively. Impressively, the PEMWE with RuSbO_x as bifunctional catalysts only needs 1.72 to reach 1.0 A cm^-2, and can maintain stable operation for 200 h at 200 mA cm^-2. The in situ Raman and molecular probe methods reveal that the single-atom Sb doping can reconstruct the interfacial water structure on the surface of RuSbO_x, resulting in an enriched supply of free water, accelerating the deprotonation process and reducing the local acidity of the catalyst surface, thereby improving the acidic OER activity and stability. Density functional theory calculations further confirm the above experimental results. In short, this work reveals that Sb is an outstanding structural stabilizer, and single-atom Sb-doping can maximize the OER stability of Ru-based catalysts in acid, which provides a useful strategy for designing ultra-stable electrocatalysts for PEMWE.