Mechanistic insights into alkali cations stabilizing carbon for acidic and high‐rate electrosynthesis of H2O2

Abstract Electrochemical two‐electron oxygen reduction reaction for H₂O₂ synthesis offers a sustainable alternative to the traditional anthraquinone. Carbon catalysts exhibit superior selectivity and industrial compatibility compared to metal‐based systems. However, their instability under acidic industrial current densities remains a challenge. While cations are known to enhance stability, their mechanistic role is poorly understood. We reveal that K + stabilizes oxidized carbon sites via the formation of interfacial KOC bonding. This bonding effectively mitigates deactivation and suppresses the undesired transition from the target H₂O₂ to the H₂O. To systematically probe this mechanism, we developed a custom rotating gas diffusion electrode system. This platform enabled stable measurements at industrial current densities. Complementarily, Raman spectroscopy and in situ near‐ambient‐pressure x‐ray photoelectron spectroscopy analyses corroborated the critical role of KOC interactions in preserving catalyst durability. Our work elucidates a cation‐mediated stabilization mechanism, advancing the design of a test platform for scalable H₂O₂ electrosynthesis.