Upgrading of nitrate to hydrazine through cascading electrocatalytic ammonia production with controllable N-N coupling

• Published in: Nature communications Vol. 15; no. 1; pp. 8567 - 11
• Main Authors: Jia, Shunhan, Zhang, Libing, Liu, Hanle, Wang, Ruhan, Jin, Xiangyuan, Wu, Limin, Song, Xinning, Tan, Xingxing, Ma, Xiaodong, Feng, Jiaqi, Zhu, Qinggong, Kang, Xinchen, Qian, Qingli, Sun, Xiaofu, Han, Buxing
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03-10-2024; Nature Publishing Group; Nature Portfolio
• Subjects: 119/118; 140/131; 140/133; 140/146; 147/135; 147/143; 639/301/299/886; 639/638/161/886; 639/638/224/685; Acetonitrile; Ammonia; Catalysts; Chemical bonds; Chemical synthesis; Conjugation; Controllability; Coupling; Dehydrogenation; Electrochemistry; Humanities and Social Sciences; Hydrazine; Hydrazines; Hydrogen bonding; Intermediates; Ketones; multidisciplinary; Nitrogen; Nitrogen cycle; Nitrogen oxides; Nitrogen sources; Photochemicals; Science; Science (multidisciplinary); Selectivity; Tungsten oxides
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-52825-1

Nitrogen oxides (NO
x
) play important roles in the nitrogen cycle system and serve as renewable nitrogen sources for the synthesis of value-added chemicals driven by clean electricity. However, it is challenging to achieve selective conversion of NO
x
to multi-nitrogen products (e.g., N
2
H
4
) via precise construction of a single N-N bond. Herein, we propose a strategy for NO
x
-to-N
2
H
4
under ambient conditions, involving electrochemical NO
x
upgrading to NH
3
, followed by ketone-mediated NH
3
to N
2
H
4
. It can achieve an impressive overall NO
x
-to-N
2
H
4
selectivity of 88.7%. We elucidate mechanistic insights into the ketone-mediated N-N coupling process. Diphenyl ketone (DPK) emerges as an optimal mediator, facilitating controlled N-N coupling, owing to its steric and conjugation effects. The acetonitrile solvent stabilizes and activates key imine intermediates through hydrogen bonding. Experimental results reveal that Ph
2
CN* intermediates formed on WO
3
catalysts acted as pivotal monomers to drive controlled N-N coupling with high selectivity, facilitated by lattice-oxygen-mediated dehydrogenation. Additionally, both WO
3
catalysts and DPK mediators exhibit favorable reusability, offering promise for green N
2
H
4
synthesis.
Nitrogen oxides are vital in the nitrogen cycle and renewable chemical synthesis, but selective conversion to multi-nitrogen products via precise N-N bond formation is challenging. Here, the authors report a two-step electrochemical process that achieves an impressive 88.7% selectivity for hydrazine production using a WO
3
catalyst with diphenyl ketone as a mediator.