Synergizing Fe2O3 nanoparticles on single atom Fe-N-C for nitrate reduction to ammonia at industrial current densities

07 November 2023, Version 1


The electrochemical reduction of oxidized nitrogen species enables a pathway for the carbon neutral synthesis of ammonia (NH3). The most oxidized form of nitrogen, nitrate (NO3-) can be reduced to NH3 via the nitrate reduction reaction (NO3RR), which has been demonstrated at high selectivity. However, to make NH3 synthesis cost-competitive with current technologies, high NH3 partial current densities (jNH3) must be achieved to reduce the levelized cost of NH3. Here, we leverage the high NO3RR activity of Fe-based materials to synthesize a novel active particle-active support system with Fe2O3 nanoparticles supported on atomically dispersed Fe-N-C. By synergizing the activity of both nanoparticles and single atom sites, the optimized 3xFe2O3/Fe-N-C catalyst demonstrates an ultrahigh NO3RR activity, reaching a maximum jNH3 of 1.95 A cm-2 at a Faradaic efficiency (FE) for NH3 of 100% and an NH3 yield rate over 9 mmol hr-1 cm-2. Operando XANES and post-mortem XPS reveal the importance of a pre-reduction activation step, reducing the surface Fe2O3 (Fe3+) to highly active Fe0 sites, which are maintained during electrolysis, to realize the ultrahigh NO3RR activity. Durability studies demonstrate the robustness of both the Fe2O3 particles and Fe-Nx sites at highly cathodic potentials, maintaining a current of -1.3 A cm-2 over 24 hours, a near unity FENH3. This work exhibits an effective and durable active particle-active support system enhancing the performance of the NO3RR, enabling industrially relevant current densities and near 100% selectivity.



Supplementary materials

Supplementary Information - Synergizing Fe2O3 nanoparticles on single atom Fe-N-C for nitrate reduction to ammonia at industrial current densities
Additional characterization (TEM, STEM, XAS, XPS, XRD, Raman, TGA), Electrochemical data (CA, LSV), Ammonia quantification (UV-Vis, NMR), Operando XAS, XPS depth profiling.


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.