Synergizing surface anchoring and hydroxylation of Ru-based electrocatalysts to balance activity-stability paradox for acidic oxygen evolution reaction

Ruthenium (Ru) catalysts define the intrinsic activity frontier for acidic oxygen evolution (OER) but suffer rapid dissolution and restructuring. This study addresses this activity–durability gap by anchoring ultra-dispersed Ru on an acid-robust CoWO₄ scaffold and preconditioning the Ru–support interface via alkaline treatment that generates a hydroxylated, wettable surface. The optimized Ru-based catalyst (20KRu@CoWO₄) achieves an overpotential of 230 mV at 10 mA cm⁻² (η₁₀) and a Tafel slope of 64 mV dec⁻¹ in 0.5 M H₂SO₄. It maintains extended operational stability with minimal Ru dissolution and outperforms both untreated and acid-conditioned controls. The enhancement mechanism has been explored by investigating the effect on surface chemistry and reaction pathway. The results of operando Raman with isotope labeling and methanol probing are consistent with an adsorbate-evolution-dominated pathway at Ru–support interfacial sites. The dual treatment yields a surface-hydroxylated, anchored Ru on CoWO₄ with a Ru–OH top layer on Ru–O–Co motifs. The –OH layer pre-activates water and serves as a proton relay, optimizing *OH/*O/*OOH energetics and accelerating proton-coupled electron transfer (PCET), while Ru–O–Co-anchoring enhances charge transfer and inhibits Ru dissolution, thereby improving both activity and durability in acidic medium. By coupling robust Ru anchoring with purposeful surface hydroxylation, this strategy reconciles high activity with durability and provides a generalizable route to Ru-efficient acidic OER catalysts.