Strain Engineering via W–O–Ru Interfacial Coupling to Suppress Lattice Oxygen Activation for Stable Acidic Water Electrolysis

Developing highly active and durable acidic oxygen evolution reaction (OER) electrocatalysts remains a central challenge for proton‐exchange membrane water electrolysis (PEMWE). Here, we combine theory‐guided design, atomic‐layer engineering, and operando spectroscopy to create a structurally robust, mechanistically tuned Ru‐based catalyst. Density functional theory reveals that depositing W 1 O 3 onto RuO 2 maximizes Ru and O vacancy formation energies, outperforming other tested transition metals. Guided by this, we employ atomic layer deposition to construct atomically coupled W–O–Ru interfacial units on RuO 2 (W–O–RuO 2 ), generating a tensile‐stressed surface while preserving the rutile core. Comprehensive in situ spectroscopy and mass spectrometry demonstrate that this architecture effectively suppresses lattice–oxygen activation, shifting the reaction from a lattice–oxygen mechanism to a more reversible adsorbate evolution mechanism. Operando x‐ray absorption spectroscopy confirms the dynamic stability of the W–O–Ru interface during OER, which evolves into a resilient, mildly compressive (1%) state without degrading. Consequently, W–O–RuO 2 demands a mere 168 mV overpotential at 10 mA cm − 2 and sustains 1 A cm − 2 in a PEMWE device for 1000 h with an ultra‐low degradation rate of 63.3 µV/h. This work establishes interfacial unit engineering as a generalizable blueprint for designing exceptionally stable acidic OER catalysts.