Ruthenium‐Based Binary Alloy with Oxide Nanosheath for Highly Efficient and Stable Oxygen Evolution Reaction in Acidic Media

Abstract Traditional noble metal oxide, such as RuO₂, is considered a benchmark catalyst for acidic oxygen evolution reaction (OER). However, its practical application is limited due to sluggish activity and severe electrochemical corrosion. In this study, Ru‐Fe nanoparticles loading on carbon felt (RuFe@CF) is synthesized via an ultrafast Joule heating method as an active and durable OER catalyst in acidic conditions. Remarkably low overpotentials of 188 and 269 mV are achieved at 10 and 100 mA cm⁻², respectively, with a robust stability up to 620 h at 10 mA cm⁻². When used as an anode in a proton exchange membrane water electrolyzer, the catalyst shows more than 250 h of stability at a water‐splitting current of 200 mA cm⁻². Experimental characterizations reveal the presence of a Ru‐based oxide nanosheath on the surface of the catalyst during OER tests, suggesting a surface reconstruction process that enhances the intrinsic activity and inhibits continuous metal dissolution. Moreover, density functional theory calculations demonstrate that the introduction of Fe into the RuFe@CF catalyst reduces the energy barrier and boosts its activities. This work offers an effective and universal strategy for the development of highly efficient and stable catalysts for acidic water splitting.