Two Orders of Magnitude Enhancement in Nitrogen Oxidation via HSO-Mediated Fe-TiO Electrocatalysis.

Electrocatalytic nitrogen oxidation emerges as a promising approach for the eco-friendly synthesis of nitrate, achieving remarkable progress in recent years. However, the precise oxidation mechanism remains poorly understood due to the complex interactions among the catalyst, electrolyte, and various intermediates, making it difficult to fully unravel the reaction pathways. Herein, we employed a Fe-TiO catalyst in electrolytes enriched with SO/HSO, significantly enhancing the nitrogen oxidation process through the in situ generation of *SOH. Remarkably, an astounding 404-fold improvement over HClO in a saturated potassium monopersulfate (PMS) system under a constant current density of 0.40 mA/cm was achieved. Furthermore, an HSO-mediated electrochemical oxidation mechanism, characterized by the high efficacy and stability of *SOH, was proposed and validated through the identification of key intermediates, comprehensive operational experiments, and in situ detection of the catalyst's active sites.