Oxygen Functional Groups Regulate Cobalt-Porphyrin Molecular Electrocatalyst for Acidic H₂O₂ Electrosynthesis at Industrial-Level Current

Electrosynthesis of hydrogen peroxide (H₂O₂) based on proton exchange membrane (PEM) reactor represents a promising approach to industrial-level H₂O₂ production, while it is hampered by the lack of high-efficiency electrocatalysts in acidic medium. Herein, we present a strategy for the specific oxygen functional group (OFG) regulation to promote the H₂O₂ selectivity up to 92 % in acid on cobalt-porphyrin molecular assembled with reduced graphene oxide. In situ X-ray adsorption spectroscopy, in situ Raman spectroscopy and Kelvin probe force microscopy combined with theoretical calculation unravel that different OFGs exert distinctive regulation effects on the electronic structure of Co center through either remote (carboxyl and epoxy) or vicinal (hydroxyl) interaction manners, thus leading to the opposite influences on the promotion in 2e^- ORR selectivity. As a consequence, the PEM electrolyzer integrated with the optimized catalyst can continuously and stably produce the high-concentration of ca. 7 wt % pure H₂O₂ aqueous solution at 400 mA cm^-2 over 200 h with a cell voltage as low as ca. 2.1 V, suggesting the application potential in industrial-scale H₂O₂ electrosynthesis.