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Towards sustainable metal-mediated ammonia electrosynthesis

Nature Energy volume 9, pages 1344–1349 (2024)Cite this article

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Abstract

Ammonia is a key component of fertilizers, a crucial industrial chemical and a carbon-free fuel. Electrosynthesis of ammonia from nitrogen under ambient conditions presents an attractive alternative to the centralized Haber–Bosch process. Although lithium- and calcium-mediated nitrogen reduction (Li-NRR and Ca-NRR) show promise, long-term continuous ammonia electrosynthesis at high rates will be needed for industrial application. In this Perspective we argue that for Li-NRR and Ca-NRR to operate sustainably, the use of continuous-flow reactors—in which NRR is coupled with the hydrogen oxidation reaction, avoiding non-sustainable proton sources and electrolyte oxidation—is essential. Providing the necessary protons via hydrogen oxidation is vital for the sustainable production of ammonia and long-term system stability. We propose strategies such as optimizing the solid–electrolyte interphase design, refining the electrode and reactor engineering to enhance the system stability and ammonia production rate. We also strongly advocate the exploration of electrocatalytic routes for surpassing the theoretical energy efficiency limit of Li/Ca-NRR.

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Fig. 1: Overcoming limitations of the batch reactor by combining HOR and NRR.
Fig. 2: Electrochemical performance in batch reactors and continuous-flow reactors.
Fig. 3: Strategies towards high-performance Li/Ca-NRR and next-generation NH3 electrosynthesis.

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Acknowledgements

We gratefully acknowledge the funding by Villum Fonden, part of the Villum Center for the Science of Sustainable Fuels and Chemicals (V-SUSTAIN grant 9455), Innovationsfonden (E-ammonia grant 9067-00010B), the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement number 741860) and MSCA European Postdoctoral Fellowships (Electro-Ammonia Project 101059643).

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  1. These authors contributed equally: Shaofeng Li, Xianbiao Fu.

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  1. Department of Physics, Technical University of Denmark, Kongens Lyngby, Denmark

    Shaofeng Li, Xianbiao Fu, Jens K. Nørskov & Ib Chorkendorff

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  1. Shaofeng Li
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  2. Xianbiao Fu
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Correspondence to Jens K. Nørskov or Ib Chorkendorff.

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Nature Energy thanks Rebecca Hodgetts and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Li, S., Fu, X., Nørskov, J.K. et al. Towards sustainable metal-mediated ammonia electrosynthesis. Nat Energy 9, 1344–1349 (2024). https://doi.org/10.1038/s41560-024-01622-7

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