Electron Transfer-Proton Supply Decoupling at Functionalized Polymer Interfaces Enables Efficient Air-Fed H₂O₂...

Air-fed electrochemical H₂O₂ production via the two-electron oxygen reduction reaction (2e^- ORR) offers a sustainable alternative to conventional processes, yet its efficiency is fundamentally constrained by low O₂ availability and intrinsically coupled electron-proton transfer. Here, we construct a bifunctional covalent organic polymer interface integrating carbonyl electron-relay units and quaternary ammonium cationic motifs on commercial carbon black (QSPIP-TMC@CB), enabling efficient H₂O₂ electrosynthesis directly from air. The QSPIP-TMC@CB delivers a H₂O₂ production rate of 3410.1 mmol·h^-1·g^-1 with 91.4% H₂O₂ Faradaic efficiency (FE_H2O2) under air, and sustains stable operation at 100.0 mA·cm^-2 for 35.0  h. Mechanistically, carbonyl motifs function as reversible redox mediators that facilitate electron injection into O₂, while quaternary ammonium cations enrich interfacial O₂ and regulate proton accessibility via Donnan repulsion, suppressing excessive protonation of the *OOH intermediate and preventing O─O bond cleavage. This cooperative regulation decouples electron transfer from proton supply, thereby stabilizing the 2e^- pathway under O₂-lean conditions. The strategy is readily extendable to representative ORR catalysts (Co─N─C and ZnO) and enables gram-scale H₂O₂ production (4.8 g h^-1 at 5.0 A, 1.0 wt% within 5 min), establishing functionalized-interface electron-proton decoupling as a general and scalable design paradigm for air-fed H₂O₂ electrosynthesis.