Electroreduction of nitrogen with almost 100% current-to-ammonia efficiency

• Published in: Nature (London) Vol. 609; no. 7928; pp. 722 - 727
• Main Authors: Du, Hoang-Long, Chatti, Manjunath, Hodgetts, Rebecca Y., Cherepanov, Pavel V., Nguyen, Cuong K., Matuszek, Karolina, MacFarlane, Douglas R., Simonov, Alexandr N.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 22.09.2022; Nature Publishing Group
• Subjects: 140/131; 140/146; 639/4077/4079/4088/4058; 639/638/161/886; Ammonia; Chemical reduction; Efficiency; Electrochemistry; Electrodes; Electrolytes; Ethanol; Experiments; Fluorides; Fossil fuels; Humanities and Social Sciences; Lithium; multidisciplinary; Nitrogen; Physicochemical properties; Robustness; Scanning electron microscopy; Science; Science (multidisciplinary); Spectrum analysis; Viscosity
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-022-05108-y

In addition to its use in the fertilizer and chemical industries 1 , ammonia is currently seen as a potential replacement for carbon-based fuels and as a carrier for worldwide transportation of renewable energy 2 . Implementation of this vision requires transformation of the existing fossil-fuel-based technology for NH 3 production 3 to a simpler, scale-flexible technology, such as the electrochemical lithium-mediated nitrogen-reduction reaction 3 , 4 . This provides a genuine pathway from N 2 to ammonia, but it is currently hampered by limited yield rates and low efficiencies 4 – 12 . Here we investigate the role of the electrolyte in this reaction and present a high-efficiency, robust process that is enabled by compact ionic layering in the electrode–electrolyte interface region. The interface is generated by a high-concentration imide-based lithium-salt electrolyte, providing stabilized ammonia yield rates of 150 ± 20 nmol s −1  cm −2 and a current-to-ammonia efficiency that is close to 100%. The ionic assembly formed at the electrode surface suppresses the electrolyte decomposition and supports stable N 2 reduction. Our study highlights the interrelation between the performance of the lithium-mediated nitrogen-reduction reaction and the physicochemical properties of the electrode–electrolyte interface. We anticipate that these findings will guide the development of a robust, high-performance process for sustainable ammonia production. A high-efficiency, robust process using a high-concentration imide-based lithium-salt electrolyte enables the electroreduction of nitrogen with stabilized ammonia yield rates of 150 ± 20 nmol s −1   cm −2 and a current-to-ammonia efficiency that is close to 100%.