Electrochemical removal of ammonium nitrogen in high efficiency and N2 selectivity using non-noble single-atomic iron catalyst

Ammonia nitrogen (NH 4 + -N) is a ubiquitous environmental pollutant, especially in offshore aquaculture systems . Electrochemical oxidation is very promising to remove NH 4 + -N, but suffers from the use of precious metals anodes. In this work, a robust and cheap electrocatalyst , iron single-atoms distributed in nitrogen-doped carbon (Fe-SAs/N-C), was developed for electrochemical removal of NH 4 + -N from in wastewater containing chloride. The Fe-SAs/N-C catalyst exhibited superior activity than that of iron nanoparticles loaded carbon (Fe-NPs/N-C), unmodified carbon and conventional Ti/IrO 2 -TiO 2 -RuO 2 electrodes. And high removal efficiency (> 99%) could be achieved as well as high N 2 selectivity (99.5%) at low current density. Further experiments and density functional theory (DFT) calculations demonstrated the indispensable role of single-atom iron in the promoted generation of chloride derived species for efficient removal of NH 4 + -N. This study provides promising inexpensive catalysts for NH 4 + -N removal in aquaculture wastewater.