Efficient and Scalable Electrochemical Energy Systems via Peroxide-Mediated Redox Chemistry

The transition to renewable energy demands cost-effective and environmentally sustainable technologies. Electrochemical redox reactions, particularly the oxygen evolution reaction and the oxygen reduction reaction, are central to energy conversion and storage systems such as metal-air batteries, electrolyzers, and fuel cells. However, the conventional four-electron O₂ redox pathway suffers from sluggish kinetics and large overpotentials, limiting both efficiency and commercial viability. An emerging alternative is the two-electron O₂ redox pathway based on reversible O₂/H₂O₂ conversion. This route offers faster kinetics, lower energy barriers, and a simpler reaction mechanism involving a single intermediate-hydrogen peroxide. This perspective reviews recent progress in two-electron O₂ redox chemistry, with an emphasis on its integration into metal-air batteries and water-splitting systems. Underlying mechanisms, materials challenges, and innovations in catalyst and electrode design that enable efficient, reversible O₂/H₂O₂ cycling are examined. Peroxide-mediated strategies offer a promising direction for overcoming the limitations of the four-electron pathway and advancing scalable, high-efficiency electrochemical energy technologies.