Decoding the Oxygen Reduction Reaction: Mechanistic Insights from Transition Metal Heterostructures

reactant, with pathway selectivity governed by atomic-scale coordination and electronic effects. This review summarizes current understanding of ORR mechanisms on transition metal-based catalysts, with a focus on how atomic-scale structural features are related to reaction activity, selectivity, and stability under different electrolyte conditions. Representative applications in metal-air batteries, fuel cells, and electrochemical hydrogen peroxide production are also discussed to illustrate how mechanistic insights are reflected in practical electrochemical systems. By distilling shared mechanistic features across different systems, this review provides a coherent framework for understanding and guiding ORR catalyst design.