Interfacial tensile strain-induced Ru–O bond regulation in lattice-matched heterostructures for robust acidic water electrolysis

Ruthenium oxide is among the most active electrocatalysts for the acidic oxygen evolution reaction (OER), yet its practical use is severely limited by anodic over-oxidation, lattice-oxygen participation, and the resulting Ru dissolution. Here, we report a monolithic RuO 2 -TiO x /Ti anode directly constructed on Ti felt through a one-step impregnation-calcination strategy, in which the native surface oxide evolves at only 400 °C into a rutile-like TiO x interlayer that is lattice-matched with rutile RuO 2 . The resulting structurally defined RuO 2 -TiO x heterointerface induces interfacial charge redistribution and tensile lattice distortion, thereby modulating the Ru–O coordination environment, attenuating Ru–O covalency, and suppressing excessive lattice-oxygen participation. Operando spectroscopy, isotope-labeling analysis, electrochemical probing, and theoretical calculations collectively reveal that such interfacial regulation shifts acidic OER toward the adsorbate-evolution mechanism while suppressing Ru overoxidation and local structural reconstruction. Beyond active-site modulation, the integrated TiO x interlayer and metallic Ti scaffold provide robust interfacial adhesion, efficient electron transport, and favorable gas/liquid transport under high-rate operation. As a result, RuO 2 -TiO x /Ti delivers an overpotential of 172 mV at 10 mA cm −2 , sustains 50 mA cm −2 for 1000 h with only 18 ppb Ru dissolution, and enables proton exchange membrane (PEM) water electrolysis at 1.65 V at 1 A cm −2 . This work highlights lattice-matched heterointerface engineering as an effective strategy for durable acidic OER electrodes. The lattice-matched RuO 2 -TiO x heterointerface induces charge redistribution and tensile distortion, elongating Ru–O bonds, reducing covalency, and suppressing lattice-oxygen participation for highly active and durable acidic oxygen evolution reaction (OER). Download: Download high-res image (145KB) Download: Download full-size image