Unveiling the chemistry behind the electrolytic production of hydrogen peroxide by oxygenated carbon

Oxygenated carbon materials exhibit outstanding electrocatalytic performance in the production of hydrogen peroxide (H2O2) through a two-electron oxygen reduction reaction. The nature of the active functional group and underlying reaction mechanism, however, remain unclear. Here, a comprehensive workflow was established to identify the active sites from the numerous possible structures. The common hydroxyl group at the notched edge demonstrates a key role in the two-electron process. The local chemical environment weakens the binding of OOH intermediate to substrate while enhancing interaction with solution, thereby promoting the H2O2 production. With increasing pH, the intramolecular hydrogen bond between OOH intermediate and hydroxyl decreases, facilitating OOH desorption. Furthermore, the rise in selectivity with increasing potential stems from the suppression of the four-electron process. The active site was further validated through experiments. Guided by theoretical understanding, optimal performance was achieved with high selectivity (>95%) and current density (2.06 mA/cm2) in experiment.