Direct Synthesis of Pure Aqueous H₂O₂ Solutions Catalyzed by C₆₀-Buffered Proton-Electron Transfer on Palladium...

The proton-electron transfer (PET) reaction is a fundamental pathway in redox catalysis that drives critical processes from enzymatic reactions to sustainable fuel generation. Yet its efficient implementation in heterogeneous systems often necessitates liquid-phase molecular mediators, which limit sustainability and simplicity. Direct H₂O₂ synthesis exemplifies this challenge, where high selectivity conventionally requires organic solvents to mediate PET and suppress side reactions. Herein, this limitation is mitigated by employing C₆₀ as a solid-state replacement for molecular mediators; we report a palladium adatom catalyst on C₆₀ that enables direct H₂O₂ synthesis in pure water, achieving an exceptional rate of 150 mol kg_cat^-1 h^-1 with 90% selectivity and a record product concentration of 0.56 wt %. The benchmark performance stems from a "C₆₀-buffered PET" mechanism, wherein C₆₀ dynamically regulates both electron density and proton/hydrogen species flux, which cooperates with the selective palladium adatom site to inhibit both O-O bond cleavage and overhydrogenation.