Synergistic Composition and Surface Engineering of Ruthenium‐Cobalt Hydroxide Nanowires for Efficient Oxygen Evolution Catalysis

Developing efficient electrocatalysts that improve the rate-determining step (RDS) kinetics is crucial to addressing the kinetically sluggish oxygen evolution reaction (OER). This study introduces ruthenium (Ru)-cobalt(II) hydroxide (Co(OH)₂) electrocatalysts for high-performance OER by combining compositional and thermodynamic surface engineering. Density functional theory (DFT) is employed to identify the ideal composition, with experimental validation conducted through electrodeposition, enabling facile control over a wide range of compositions for nanowire catalyst synthesis. Pourbaix diagram analysis helps establish precise synthesis conditions for developing surface nanostructures. The optimized Ru-Co(OH)₂ catalyst demonstrates exceptional performance, achieving overpotentials of 189 mV at 10 mA cm⁻² and 292 mV at 50 mA cm⁻², significantly outperforming other compositions. The exceptional electrocatalytic performance can be attributed to two key factors: strengthened OH adsorption energy due to optimal composition, which lowers the energy barrier of the rate-determining step in the OER, and increased specific surface area resulting from surface nanostructure formation.