Sustainable conversion of alkaline nitrate to ammonia at activities greater than 2 A cm−2

• Published in: Nature communications Vol. 15; no. 1; pp. 1264 - 12
• Main Authors: Liao, Wanru, Wang, Jun, Ni, Ganghai, Liu, Kang, Liu, Changxu, Chen, Shanyong, Wang, Qiyou, Chen, Yingkang, Luo, Tao, Wang, Xiqing, Wang, Yanqiu, Li, Wenzhang, Chan, Ting-Shan, Ma, Chao, Li, Hongmei, Liang, Ying, Liu, Weizhen, Fu, Junwei, Xi, Beidou, Liu, Min
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.02.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 140/133; 140/146; 639/638/77/886; 704/172/169; Ammonia; Ammonium chloride; Chemical reduction; Desorption; Efficiency; Humanities and Social Sciences; Hydrogen; Hydrogenation; multidisciplinary; Nitrates; Science; Science (multidisciplinary); Water quality
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-45534-2

Nitrate (NO 3 ‒ ) pollution poses significant threats to water quality and global nitrogen cycles. Alkaline electrocatalytic NO 3 ‒ reduction reaction (NO 3 RR) emerges as an attractive route for enabling NO 3 ‒ removal and sustainable ammonia (NH 3 ) synthesis. However, it suffers from insufficient proton (H + ) supply in high pH conditions, restricting NO 3 ‒ -to-NH 3 activity. Herein, we propose a halogen-mediated H + feeding strategy to enhance the alkaline NO 3 RR performance. Our platform achieves near-100% NH 3 Faradaic efficiency (pH = 14) with a current density of 2 A cm –2 and enables an over 99% NO 3 – -to-NH 3 conversion efficiency. We also convert NO 3 ‒ to high-purity NH 4 Cl with near-unity efficiency, suggesting a practical approach to valorizing pollutants into valuable ammonia products. Theoretical simulations and in situ experiments reveal that Cl-coordination endows a shifted d -band center of Pd atoms to construct local H + -abundant environments, through arousing dangling O-H water dissociation and fast *H desorption, for *NO intermediate hydrogenation and finally effective NO 3 ‒ -to-NH 3 conversion. Alkaline nitrate electroreduction to ammonia is restricted by insufficient H + supply. Here, the authors propose a halogen-mediated H + feeding strategy, by triggering dangling O-H water dissociation and fast *H desorption for *NO intermediate hydrogenation, to enhance the formation of ammonia.