Engineering the electronic structure of single atom Ru sites via compressive strain boosts acidic water oxidation electrocatalysis

Single-atom precious metal catalysts hold the promise of perfect atom utilization, yet control of their activity and stability remains challenging. Here we show that engineering the electronic structure of atomically dispersed Ru ₁ on metal supports via compressive strain boosts the kinetically sluggish electrocatalytic oxygen evolution reaction (OER), and mitigates the degradation of Ru-based electrocatalysts in an acidic electrolyte. We construct a series of alloy-supported Ru ₁ using different PtCu alloys through sequential acid etching and electrochemical leaching, and find a volcano relation between OER activity and the lattice constant of the PtCu alloys. Our best catalyst, Ru ₁ –Pt ₃ Cu, delivers 90 mV lower overpotential to reach a current density of 10 mA cm ⁻² , and an order of magnitude longer lifetime over that of commercial RuO ₂ . Density functional theory investigations reveal that the compressive strain of the Pt _skin shell engineers the electronic structure of the Ru ₁ , allowing optimized binding of oxygen species and better resistance to over-oxidation and dissolution.