Two Orders of Magnitude Enhancement in Nitrogen Oxidation via H₂SO₄-Mediated Fe-TiO₂ Electrocatalysis.

Abstract

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-TiO₂ catalyst in electrolytes enriched with SO₄^2-/HSO₅^-, significantly enhancing the nitrogen oxidation process through the in situ generation of *SO₅H. Remarkably, an astounding 404-fold improvement over HClO₄ in a saturated potassium monopersulfate (PMS) system under a constant current density of 0.40 mA/cm² was achieved. Furthermore, an H₂SO₄-mediated electrochemical oxidation mechanism, characterized by the high efficacy and stability of *SO₅H, was proposed and validated through the identification of key intermediates, comprehensive operational experiments, and in situ detection of the catalyst's active sites.