Strain‐modulated Ru‐O Covalency in Ru‐Sn Oxide Enabling Efficient and Stable Water Oxidation in Acidic Solution

Abstract RuO 2 is one of the benchmark electrocatalysts used as the anode material in proton exchange membrane water electrolyser. However, its long‐term stability is compromised due to the participation of lattice oxygen and metal dissolution during oxygen evolution reaction (OER). In this work, weakened covalency of Ru−O bond was tailored by introducing tensile strain to RuO 6 octahedrons in a binary Ru−Sn oxide matrix, prohibiting the participation of lattice oxygen and the dissolution of Ru, thereby significantly improving the long‐term stability. Moreover, the tensile strain also optimized the adsorption energy of intermediates and boosted the OER activity. Remarkably, the RuSnO x electrocatalyst exhibited excellent OER activity in 0.1 M HClO 4 and required merely 184 mV overpotential at a current density of 10 mA cm −2 . Moreover, it delivered a current density of 10 mA cm −2 for at least 150 h with negligible potential increase. This work exemplifies an effective strategy for engineering Ru‐based catalysts with extraordinary performance toward water splitting.