Encapsulation-Driven Stabilization of RuCo Alloy Catalysts for Acidic Oxygen Evolution Reaction

Achieving simultaneously high activity and long-term durability for the oxygen evolution reaction (OER) under acidic conditions remains a key materials challenge for proton exchange membrane water electrolysis (PEMWE). Herein, we report a core-shell electrocatalyst, RuCo@NC, composed of a partially ordered RuCo alloy core encapsulated by a nitrogen-doped carbon (NC) shell, synthesized through sequential solution plasma processing and ionic liquid coating. Benefiting from the protective carbon encapsulation and metal-nitrogen interfacial interactions, RuCo@NC exhibits competitive OER performance in acidic media, delivering a low overpotential of 221 mV at 10 mA cm^-2 and a Tafel slope of 76.4 mV dec^-1. Notably, the catalyst demonstrates enhanced durability, retaining 87% of its initial activity after 165 min continuous operation. Structural and spectroscopic analyses, supported by density functional theory calculations, indicate that the NC shell modulates the electronic structure of the RuCo alloy through interfacial Ru-N interactions, leading to optimized adsorption energetics and suppressed metal dissolution during operation. This work highlights carbon encapsulation as an effective materials design strategy to stabilize Ru-based alloy catalysts while maintaining high OER activity in acidic environments, offering practical insights for the development of durable electrocatalysts for PEMWE.