Suppressing Ru Deactivation Through Lattice Hydrogen and Hydroxyl Adsorption Engineering for High-Performing Alkaline Fuel Cells

Ru-based catalysts demonstrate attractive activity and cost advantages for alkaline hydrogen oxidation reaction (HOR), yet their practical deployment is limited by rapid deactivation at high anodic potentials in fuel cells. Here we identify reversible hydroxyl-related surface passivation, particularly excessive *OH accumulation, as a key contributor to high-potential Ru deactivation, and demonstrate that it can be mitigated through coupled regulation of *OH coverage and interfacial hydrogen supply. Guided by this mechanistic insight, we design a Pd-core, tetra-element-ensemble Ru skin catalyst (Pd@Tees Ru), where electronic modulation of the multimetallic Ru shell suppresses excessive *OH accumulation, while the Pd core serves as a dynamic lattice-hydrogen reservoir. Electrochemical evidence reveals the anodic release of interstitial hydrogen from the Pd core, sustaining *H coverage at the active interface and mitigating excessive accumulation of hydroxyl-related surface species. Such synergistic interfacial regulation enables sustained HOR activity at potentials above 0.5 V. An anion-exchange membrane fuel cell with the Pd@Tees Ru anode achieves a peak power density of 1.78 W cm^-2 under H₂/O₂ conditions and operates stably for 200 h at 500 mA cm^-2. By integrating lattice-hydrogen dynamics with surface adsorption thermodynamics, this work provides a general strategy for mitigating passivation and improving the durability of Ru-based electrocatalysts.