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

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 W₁O₃ onto RuO₂ 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 RuO₂ (W-O-RuO₂), 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-RuO₂ 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.