Electrocatalytic Reactive Capture of NO from O₂-Containing Simulated Flue Gas Using Highly O₂-Resistant Fe²⁺-(salen-SO₃) for NH₃ Synthesis

High Resolution Image Download MS PowerPoint Slide Efficient removal of nitric oxide (NO) from flue gases remains a significant environmental challenge due to its low concentration, poor water solubility, and the presence of oxygen, which deactivates traditional NO absorbents such as Fe 2+ -EDTA. Herein, we present an electrochemistry-based reactive NO capture system using SO 3 -functionalized Fe 2+ -salen as an NO absorbent with outstanding oxygen resistance. The unique tetracoordinate structure of the salen-SO 3 ligand reduces the electron density at the Fe 2+ center, preventing its oxidation to Fe 3+ under air exposure. Coupled with highly porous NiMo electrocatalysts, the system achieves an NH 3 production rate of 2.0 mmol h –1 cm –2 geo with 97% Faraday efficiency under 100% NO. This continuous NO capture and conversion into NH 3 was maintained under air-exposed conditions at 60% of the performance level under 100% NO, with stability over 160 h. Mechanistic studies reveal that Fe 2+ is the critical active site for NO reduction and elucidate complete reaction pathways for NH 3 synthesis.