Electronic Control of Traditional Iron-Carbon Electrodes to Regulate the Oxygen Reduction Route to Scale Up Water Purification.

Shifting four-electron (4e - ) oxygen reduction in fuel cell technology to a two-electron (2e - ) pathway with traditional iron-carbon electrodes is a critical step for hydroxyl radical (HO • ) generation. Here, we fabricated iron-carbon aerogels with desired dimensions (e.g., 40 cm × 40 cm) as working electrodes containing atomic Fe sites and Fe 3 C subnanoclusters. Electron-donating Fe 3 C provides electrons to FeN 4 through long-range activation for achieving the ideal electronic configuration, thereby optimizing the binding energy of the *OOH intermediate. With an iron-carbon aerogel benefiting from finely tuned electronic density, the selectivity of 2e - oxygen reduction increased from 10 to 90%. The resultant electrode exhibited unexpectedly efficient HO • production and fast elimination of organics. Notably, the kinetic constant k M for sulfamethoxazole (SMX) removal is 60 times higher than that in a traditional iron-carbon electrode. A flow-through pilot device with the iron-carbon aerogel (SA-Fe 0.4 NCA) was built to scale up micropolluted water decontamination. The initial total organic carbon (TOC) value of micropolluted water was 4.02 mg L -1 , and it declined and maintained at 2.14 mg L -1 , meeting the standards for drinking water quality in China. Meanwhile, the generation of emerging aromatic nitrogenous disinfection byproducts (chlorophenylacetonitriles) declined by 99.2%, satisfying the public safety of domestic water. This work provides guidance for developing electrochemical technologies to satisfy the flexible and economic demand for water purification, especially in water-scarce areas.