Ambient Electrosynthesis of Pure 15 wt% H 2 O 2 Without Salt Using an Ultrathin Metal–Organic Framework Nanosheet Featuring Dicopper(I) Active Sites

Electrochemical synthesis of hydrogen peroxide (H 2 O 2 ) is a promising alternative to the industrial anthraquinone process. Although current systems achieve near 100% selectivity and reach 300 mA cm −2 current density, the resulting H 2 O 2 often has low concentration or contains electrolyte impurities, requiring additional purification for practical use. We developed an ultrathin nanosheet (∼2.75 nm) with dicopper(I) sites (Cu‐tz NS) as an efficient electrocatalyst for the 2e − oxygen reduction reaction to produce high‐purity H 2 O 2 . Interestingly, Cu‐tz NS achieves excellent selectivity (95%–97%) and current density (up to 350 mA cm −2 at −0.3 V vs. RHE) in the flow‐cell, maintaining a yield rate of 17 mol g cat −1 h −1 over 70 hours. In a membrane electrode assembly solid–solid electrolyte system, it continuously produces pure 15 wt% H 2 O 2 without salt at 2 V over 50 hours, effectively avoiding ionic or organic contamination. Importantly, such H 2 O 2 concentration is three times higher than the average value reported in the literature. Mechanistic studies reveal a dual‐enhancement mechanism of Cu‐tz NS: (i) dicopper(I) sites promote *OOH intermediate formation, enhancing reaction kinetics; and (ii) the ultrathin MOF structure optimizes active site exposure, synergistically maximizing catalytic efficiency.