Chaos of Active Site Structure as a Ladder to Climbing the Apex of the 2e^-ORR Volcano Plot

Two-electron oxygen reduction reaction (2e^-ORR) in neutral media offers an eco-friendly and practical strategy for efficient synthesis of hydrogen peroxide (H₂O₂), yet limited understanding of electrocatalytic mechanisms and poor catalyst activity hinder its development. We propose a strategic design principle for high-performance four-coordinated Co single-atom catalysts based on atomic entropy fluctuation by both geometric and electronic modifications, quantitatively described by the descriptor φ, which is able to capture the impact of local entropy fluctuations on catalytic performance. φ serves as an effective metric for elucidating the relationship between ORR activity and the coordination environment in Co single-atom catalyst systems, thereby elucidating the origin of the high activity of CoN₃S, which lies close to the apex of the volcano peak. Based on the prediction, the as-synthesized Co-N₃SC catalyst achieved a 97% selectivity for H₂O₂ electrosynthesis at low overpotentials in neutral electrolytes. Impressively, Co-N₃SC exhibited remarkable stability and delivered a cumulative yield of 10.58 g of H₂O₂ in flow cell devices (110 h @0.18A). In a solid-state electrolyte electrolyzer, it achieved a production rate of 10.25 mol g_cat^-1 h^-1, enabling the direct synthesis of high-purity urea peroxide. This work offers not only strategies for designing highly active and selective 2e^-ORR catalysts but deep insights into coordination environment-activity regulation and validation of practical catalyst applications.