Sm-doped RuO ₂ electrocatalysts for an acidic oxygen evolution reaction: enhanced activity and stability <i>via</i> electronic structure modulation and oxygen vacancy introduction

Proton exchange membrane water electrolysis (PEMWE) is a promising hydrogen production technology, due to its high current density, high efficiency, and compact configuration. Enhancing the performance and stability of oxygen evolution reaction (OER) catalysts in acidic environments is crucial for advancing PEMWE. In this study, we developed a Sm-doped RuO₂ (Sm-RuO₂) electrocatalyst using the sol-gel method. This catalyst's large specific surface area and numerous active sites significantly enhance its activity and stability. Detailed studies show that Sm doping optimizes the electronic structure of RuO₂, fine-tunes the adsorption free energy of reaction intermediates, and creates oxygen vacancies, boosting intrinsic activity and preventing Ru over-oxidation. The experimental results show that Sm-RuO₂ follows the AEM and exhibits remarkable stability during the OER process. The stronger *OH adsorption onto the active sites accelerates the reaction. The representative Sm-RuO₂ achieves an overpotential of 219 mV at 10 mA cm^-2, outperforming undoped RuO₂ (280 mV), and operates stably for 50 h. This work provides new insights into designing high-performance electrocatalysts through electronic structure and oxygen vacancy modulation.