Searching for the Rules of Electrochemical Nitrogen Fixation

16 August 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Li-mediated ammonia synthesis is – thus far – the only electrochemical method for decentralised ammonia production, an alternative to one of the largest thermal heterogeneous catalytic processes, for its unique selectivity on a solid electrode. However, it is burdened with intrinsic energy losses, operating at Li plating potential. In this work, we survey the periodic table to understand the fundamental features that make Li stand out. Through density functional theory calculations and experimentation on chemistries analogous to lithium (e.g. Na, Mg, Ca), we find that lithium is unique in several ways. It combines a stable nitride that readily decomposes to ammonia, with an ideal solid electrolyte interphase, balancing reagents at the reactive interface. We propose descriptors based on simulated formation and binding energies of key intermediates, and further on hard and soft acids and bases (HSAB principle) to generalize such features. The survey aims to help the community towards new electrochemical systems for nitrogen fixation.


Nitrogen Fixation
Nitrogen Reduction
Ammonia Synthesis
Solid-electrolyte Interphase
HSAB principle

Supplementary materials

Supplementary Information
The following files are available free of charge. Materials; experimental methods (electrochemistry, quantification, isotope labeled studies setup, results of the electrolytic screening of Li, Na, Ca and Mg electrolytes, ToF-SIMS characterisation of Mg electrodes, electrochemistry – mass spectrometry study of Mg and Li electrolytes) and respective accompanying figures; Tabled results of the DFT calculations, with literature data on standard reduction potentials, minerals global production and HSAB acidity scale. (PDF) DFT calculation scripts (, GitHub repository)

Supplementary weblinks


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.