Doped RuO₂ for Acidic Oxygen Evolution Reaction: From Transitional Metals, Main-Group Metals to Nonmetals

The oxygen evolution reaction (OER) in acidic media is a critical bottleneck for proton exchange membrane water electrolyzers (PEMWEs), primarily due to the scarcity of electrocatalysts that combine high activity with exceptional stability. RuO₂, renowned for its superior intrinsic activity, faces significant challenges, including poor operational stability caused by over-oxidation to soluble RuO₄. Heteroatom doping has emerged as a powerful and versatile strategy to address these limitations by precisely tuning the electronic structure, optimizing intermediate adsorption energetics, and stabilizing the RuO₂ lattice. This review provides a comprehensive overview of recent advances in heteroatom-doped RuO₂ for acidic OER. We systematically categorize and discuss doping strategies based on the type of dopants-spanning transition metals, main-group metals, and non-metals. For each category, we elucidate how specific dopants influence the electronic configuration, modify active sites, and alter the OER reaction pathways, thereby enhancing both catalytic activity and durability. By synthesizing key findings from experimental and theoretical studies, this review establishes clear structure-activity relationships and offers mechanistic insights into the performance enhancements. Finally, existing challenges and future perspectives are outlined for the rational design of high-performance, doped RuO₂, aiming to accelerate their application in efficient and stable PEMWE systems for green hydrogen production.