Osmium atomic sites on CuS nanoplates for efficient two-electron oxygen reduction into H2O2

Electrocatalytic hydrogen peroxide (H₂O₂) production from O₂ reduction is attractive because of its wide applications; however, the lack of efficient and selective electrocatalysts hinders its further development. Herein, we have created a class of electrocatalysts by anchoring osmium (Os) single atomic sites on ultrathin copper sulfide nanoplates (Os₁-CuS NPs) to greatly boost the electroreduction of O₂ into H₂O₂ via a two-electron pathway. The Os single-atomic-site catalyst with sulfur coordination achieved a record-high Os loading (25.9 wt %) and an exceptional H₂O₂ production rate (8.2 mol g_cat⁻¹ h⁻¹) with near-perfect selectivity (∼98%), making it a top performer among metal-based electrocatalysts. In situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and density functional theory (DFT) calculations revealed that the introduced Os sites promote a selective 2e⁻ oxygen reduction pathway by strengthening OOH binding and thus suppressing the undesired 4e⁻ pathway. This study advances the design of high-performance single-atomic-site electrocatalysts for selective H₂O₂ generation.