Cation-tuned acidic electrified interface for hydrogen peroxide electrosynthesis with industrial-level current...

Electrocatalytic oxygen reduction reaction in seawater represents a sustainable approach for hydrogen peroxide (H₂O₂) production, yet industrial-level current densities trigger severe cathodic alkalization and scaling issues, while aggressive acidification of the reaction system compromises catalytic efficiency. Here we show a cationic modification strategy that dynamically modulates the acidic electrified interface to promote both the formation and desorption of the key *OOH intermediate for H₂O₂ synthesis. Enabled by this strategy, the cationic-modified catalysts achieve >90% efficiency at 500 mA cm^-2 in natural seawater, and even reach 1.125 A cm^-2 in high-salinity electrolytes, with a competitive estimated cost of $0.64 per kilogram of H₂O₂. Ab initio molecular dynamics simulations reveal that the introduced cationic modifications effectively counteract O-O bond cleavage induced by both the inherent strong binding of catalytic sites and the potential-induced over-binding effect under highly negative potentials, and thus facilitate *OOH desorption for H₂O₂ formation. This work highlights dynamic interfacial intermediate stabilization as a strategy that complements conventional static binding-energy tuning, enabling high-current-density H₂O₂ electrosynthesis in seawater.