Donutlike RuCu Nanoalloy with Ultrahigh Mass Activity for Efficient and Robust Oxygen Evolution in Acid Solution

Rationally architectural design and accessible construction of an efficient electrocatalyst featuring with high activity and stability in acid solution are fundamentally important to advance the renewable energy conversion technologies nowadays. Herein, we deliberately conceive and successfully synthesize a donutlike architecture of RuCu bimetallic nanoalloy with well-defined nanoscale shell by a facile “galvanic replacement” strategy to boost Ru-based electrocatalysts with prominent water oxidation performance in an acid condition. The as-prepared donutlike RuCu nanostructures with an ultrathin shell of ∼1 nm thickness could catalyze the oxygen evolution reaction (OER) under a small overpotential of 270 mV at 10 mA·cm^–2 with excellent long-term stability and ultrahigh mass activity of ∼1000 A·g_Ru^–1, two-orders of magnitude larger than Ru and commercial RuO₂ nanoparticles. Experimental and theoretical analyses reveal that the well-dispersed Cu element plays a key role in the architectural engineering and catalytic activity improvement of donutlike RuCu nanoalloy catalysts via dual regulation of coordination environment and electron structure of Ru active sites. Especially, by the merits of ultrathin shell structure, the strong surface electron transfer via robust Ru–Cu bonds could effectively promote the appearance of active and stable Ru²⁺ throughout donutlike RuCu nanoalloy, resulting in much more thermodynamically favor for H₂O adsorption and *OOH formation during OER process compared with metallic Ru nanoparticle. Undoubtedly, this approach may open a new avenue for strategically designing highly active and performance-oriented electrocatalytic materials for tremendous energy applications.