Tailoring the Surface of Perovskite through In Situ Growth of Ru/RuO2 Nanoparticles as Robust Symmetrical Electrodes for Reversible Solid Oxide Cells

Abstract Although numerous perovskite oxides can enhance the electrochemical activity via exsolved metallic nanoparticles on the surface, most of them can only be applied as catalysts in a reducing atmosphere. These nanoparticles cause serious performance degradation in oxidizing conditions due to the formation of low‐conductive metal oxides. This poses a big challenge to the design of highly active catalysts of electrochemical devices, especially for symmetrical solid oxide cells. Herein, based on the strategy of exsolved metallic nanoparticles in A‐site deficient perovskite, a unique and simple method is demonstrated for the synthesis of Ru/RuO 2 nanoparticles on the surface of perovskite oxide via in situ growth. The electrode material (La 0.75 Sr 0.25 ) 0.9 Cr 0.5 Mn 0.45 Ru 0.05 O 3− δ (LSCMR) is designed through careful choice of composition and the core idea is to make use of the exsolved nanoparticles concept applied for the first time at both hydrogen electrode and oxygen electrode for symmetrical solid oxide cells. Inspired by exsolved Ru and RuO 2 , the surface‐decorated LSCMR exhibits significantly enhanced electrochemical activity for both H 2 and O 2 , respectively, accompanied by high redox long‐term stability. Moreover, simple, low‐cost, and environmental‐friendly synthesis of Ru/RuO 2 nanoparticles on the substrate of typical perovskites is realized with this in situ growth approach.