The Strong Electronic Metal-Support Interactions Mediated Direct Three-Electron Oxygen Reduction for Enhanced Hydroxyl Radical Generation.

Hydroxyl radical (·OH) production in the traditional electro-Fenton process relies on the two-electron oxygen reduction reaction (2e- ORR) to generate H2O2, followed by activation by ferrous ions, suffering from low efficiency and mass-transfer limitations. Herein, we demonstrate that the strong electronic metal-support interactions (EMSIs) established between FeOCl and a composite carbon (GC) support could steer the 2e- ORR toward a direct 3e- ORR pathway, boosting the yield of ·OH. Combined characterizations and DFT calculations revealed that the average net charge on Fe atoms was increased owing to charge redistribution within the FeOCl driven by the strong EMSIs, enabling the optimized adsorption of O2 and key intermediates (*OOH and *HOOH), thus facilitating the efficient ·OH generation. The resulting FeOCl/GC 3e- ORR system achieved a ·OH yield of 128.8 µmol gcat -1 min-1, which was seven times that of the conventional Fe2O3/GC electro-Fenton system, allowing rapid water decontamination with an apparent rate constant of 1.15 min-1. Moreover, the sufficient ·OH production realized over 90% decontamination efficiency retained after 25 cycles, highlighting its potential for practical application. This work establishes strong EMSIs as a powerful strategy for regulating ORR pathways to enhance ·OH generation in the electro-Fenton system.