Lattice Distortion Controlled Oxygen Ion Transport Governs Interlayer Stability and OER Kinetics in Sn–Sb–RuO_x/β-PbO₂ Anodes

Porous \(\beta\)-PbO₂ anodes supported on Ti are attractive OER electrocatalysts for zinc electrowinning, yet lifetime is limited by interfacial TiO₂ growth and chloride-assisted radical chemistry. Here we provide a mechanistic account of the stabilizing role of Ru in Sn–Sb–RuO_x interlayers. Combining density functional theory with nudged elastic band (DFT/NEB) calculations, depth-resolved XPS/ToF-SIMS, electrochemical impedance spectroscopy (EIS), and accelerated ageing, we show that Ru substitution in a rutile-like SnO₂:Sb matrix introduces local lattice distortion that increases the oxygen-ion migration barrier \(\Delta G^{\ddagger}_{\mathrm{mig}}\) by 100 meV, from 0.60 ± 0.03 eV (Ru-free) to 0.70 ± 0.04 eV (1.0 at.% Ru). The higher barrier reduces O^2- flux toward Ti, suppressing sub-stoichiometric TiO_2-\(\delta\) formation and lowering both film resistance and charge-transfer resistance during OER: \(R_f\) decreases from 0.12 ± 0.02 Ω cm² to 0.08 ± 0.01 Ω cm², and \(R_{ct}\) from 60 ± 7 Ω cm² to 40 ± 5 Ω cm². Under 150 g   L⁻¹ H₂SO₄ with 1.0 mg L⁻¹ Cl^– at 40 °C, the early-time \(R_f\) drift rate improves from 1.0 ± 0.2 mΩ cm² h⁻¹ to 0.65 ± 0.15 mΩ cm² h⁻¹, extending the time-to-threshold (+200 mV rise) from 65 ± 8 h to 95 ± 10 h. We establish quantitative correlations among Ru at.%, \(\Delta G^{\ddagger}_{\mathrm{mig}}\), interfacial TiO₂ growth, and lifetime, elevating Ru from a mere “conductive dopant” to a lattice-transport regulator and yielding design rules for Ru-lean interlayers that preserve durability and performance.