Menny Shalom

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.