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Revealing nitrogen-containing species in commercial catalysts used for ammonia electrosynthesis

A Publisher Correction to this article was published on 22 February 2021

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Stimulated by the growing demand for sustainable and/or economical distributed ammonia synthesis, the electrochemical nitrogen reduction reaction has attracted considerable interest. The nitrogen-containing impurities in commercial metal-based nitrogen reduction reaction catalysts such as metal oxides and metallic irons have, however, been overlooked. Herein we report the presence of nitrogen-containing species in NOx or nitrides at substantial levels revealed from many commercial catalysts. We call attention to the necessity to screen the NOx/nitrides impurities in commercial catalysts, as the nitrogen impurities are not commonly listed in vendors’ assay documents. A simple two-step procedure (alkaline/acidic treatment followed by HPLC/UV–vis analysis) is recommended as a reliable protocol for screening NOx/nitrides impurities in catalyst materials. A case analysis is also carried out on the previously reported H2O–NaOH–KOH system with both 15N-isotopic labelling and nitrogen elemental tracking, reassigning the true nitrogen source of the electrochemically produced NH3 from gaseous N2 to nitrogen-containing impurities in catalysts.

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Fig. 1: NOx impurities detected in commercial metal oxides.
Fig. 2: Revealing nitrogen-containing impurities in commercial metal oxides and metallic irons.
Fig. 3: Electrolysis in the H2O–NaOH–KOH systems.
Fig. 4: Area- and mass-normalized NH3 production of reported NRR electrocatalysts.

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Source data are provided with this paper. All data supporting the findings of this study are available from the corresponding author on reasonable request.

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  1. Apodaca, L. E. Nitrogen (Fixed)—Ammonia. U.S. Geological Survey, Mineral Commodity Summaries (2020).

  2. Nørskov, J., Chen, J., Miranda, R., Fitzsimmons, T. & Stack, R. Sustainable Ammonia SynthesisExploring the Scientific Challenges Associated with Discovering Alternative, Sustainable Processes for Ammonia Production (US DOE Office of Science, 2016).

  3. Wang, L. et al. Greening ammonia toward the solar ammonia refinery. Joule 2, 1055–1074 (2018).

    Article  CAS  Google Scholar 

  4. Foster, S. L. et al. Catalysts for nitrogen reduction to ammonia. Nat. Catal. 1, 490–500 (2018).

    Article  Google Scholar 

  5. Soloveichik, G. Electrochemical synthesis of ammonia as a potential alternative to the Haber–Bosch process. Nat. Catal. 2, 377–380 (2019).

    Article  CAS  Google Scholar 

  6. Chen, J. G. et al. Beyond fossil fuel-driven nitrogen transformations. Science 360, eaar6611 (2018).

  7. Martín, A. J., Shinagawa, T. & Pérez-Ramírez, J. Electrocatalytic reduction of nitrogen: from Haber–Bosch to ammonia artificial leaf. Chem 5, 263–283 (2019).

    Article  Google Scholar 

  8. Tang, C. & Qiao, S.-Z. How to explore ambient electrocatalytic nitrogen reduction reliably and insightfully. Chem. Soc. Rev. 48, 3166–3180 (2019).

    Article  CAS  Google Scholar 

  9. Shipman, M. A. & Symes, M. D. Recent progress towards the electrosynthesis of ammonia from sustainable resources. Catal. Today 286, 57–68 (2017).

    Article  CAS  Google Scholar 

  10. Greenlee, L. F., Renner, J. N. & Foster, S. L. The use of controls for consistent and accurate measurements of electrocatalytic ammonia synthesis from dinitrogen. ACS Catal. 8, 7820–7827 (2018).

    Article  CAS  Google Scholar 

  11. Suryanto, B. H. R. et al. Challenges and prospects in the catalysis of electroreduction of nitrogen to ammonia. Nat. Catal. 2, 290–296 (2019).

    Article  CAS  Google Scholar 

  12. Andersen, S. Z. et al. A rigorous electrochemical ammonia synthesis protocol with quantitative isotope measurements. Nature 570, 504–508 (2019).

    Article  CAS  Google Scholar 

  13. Du, H.-L., Gengenbach, T. R., Hodgetts, R., MacFarlane, D. R. & Simonov, A. N. Critical assessment of the electrocatalytic activity of vanadium and niobium nitrides toward dinitrogen reduction to ammonia. ACS Sustain. Chem. Eng. 7, 6839–6850 (2019).

    Article  CAS  Google Scholar 

  14. Hu, B., Hu, M., Seefeldt, L. & Liu, T. L. Electrochemical dinitrogen reduction to ammonia by Mo2N: catalysis or decomposition? ACS Energy Lett. 4, 1053–1054 (2019).

    Article  CAS  Google Scholar 

  15. Zhao, Y. et al. Ammonia detection methods in photocatalytic and electrocatalytic experiments: how to improve the reliability of NH3 production rates? Adv. Sci. 6, 1802109 (2019).

    Article  Google Scholar 

  16. Manjunatha, R., Karajić, A., Teller, H., Nicoara, K. & Schechter, A. Electrochemical and chemical instability of vanadium nitride in the synthesis of ammonia directly from nitrogen. ChemCatChem 12, 438–443 (2020).

    Article  CAS  Google Scholar 

  17. Wang, Y. et al. Generating defect-rich bismuth for enhancing the rate of nitrogen electroreduction to ammonia. Angew. Chem. Int. Ed. 58, 9464–9469 (2019).

    Article  CAS  Google Scholar 

  18. Lv, C. et al. An amorphous noble-metal-free electrocatalyst that enables nitrogen fixation under ambient conditions. Angew. Chem. Int. Ed. 57, 6073–6076 (2018).

    Article  CAS  Google Scholar 

  19. Licht, S. et al. Ammonia synthesis by N2 and steam electrolysis in molten hydroxide suspensions of nanoscale Fe2O3. Science 345, 637–640 (2014).

    Article  CAS  Google Scholar 

  20. Zhou, F. et al. Electro-synthesis of ammonia from nitrogen at ambient temperature and pressure in ionic liquids. Energy Environ. Sci. 10, 2516–2520 (2017).

    Article  CAS  Google Scholar 

  21. Hu, L. et al. Ambient electrochemical ammonia synthesis with high selectivity on Fe/Fe oxide catalyst. ACS Catal. 8, 9312–9319 (2018).

    Article  CAS  Google Scholar 

  22. Furuya, N. & Yoshiba, H. Electroreduction of nitrogen to ammonia on gas-diffusion electrodes loaded with inorganic catalyst. J. Electroanal. Chem. Interfacial Electrochem. 291, 269–272 (1990).

    Article  CAS  Google Scholar 

  23. Gadalla, A. M. & Yu, H. F. Thermal decomposition of Fe(iii) nitrate and its aerosol. J. Mater. Res. 5, 1233–1236 (1990).

    Article  CAS  Google Scholar 

  24. Kodama, H. Synthesis of a new compound, Bi5O7NO3, by thermal decomposition. J. Solid State Chem. 112, 27–30 (1994).

    Article  CAS  Google Scholar 

  25. Sarkas, H., Murray, P., Fay, A. & Brotzman, R. Nanocrystalline mixed metal oxides—novel oxygen storage materials. MRS Proc. 788, L4.8 (2011).

  26. Birkeland, K. On the oxidation of atmospheric nitrogen in electric arcs. Trans. Faraday Soc. 2, 98–116 (1906).

    Article  CAS  Google Scholar 

  27. Smil, V. Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation of World Food Production 62–64 (MIT Press, 2004).

  28. Verdouw, H., Van Echteld, C. J. A. & Dekkers, E. M. J. Ammonia determination based on indophenol formation with sodium salicylate. Water Res. 12, 399–402 (1978).

    Article  CAS  Google Scholar 

  29. Ertl, G., Huber, M. & Thiele, N. Formation and decomposition of nitrides on iron surfaces. Z. fur Naturforsch. A 34, 30–39 (1979).

    Article  Google Scholar 

  30. Torres, J., Perry, C. C., Bransfield, S. J. & Fairbrother, D. H. Low-temperature oxidation of nitrided iron surfaces. J. Phys. Chem. B 107, 5558–5567 (2003).

    Article  CAS  Google Scholar 

  31. Baltrusaitis, J., Jayaweera, P. M. & Grassian, V. H. XPS study of nitrogen dioxide adsorption on metal oxide particle surfaces under different environmental conditions. Phys. Chem. Chem. Phys. 11, 8295–8305 (2009).

    Article  CAS  Google Scholar 

  32. Davies, J. A., Boucher, D. L. & Edwards, J. G. The question of artificial photosynthesis of ammonia on heterogeneous catalysts. Adv. Photochem. 19, 235–310 (1995).

    CAS  Google Scholar 

  33. Li, L., Tang, C., Yao, D., Zheng, Y. & Qiao, S.-Z. Electrochemical nitrogen reduction: identification and elimination of contamination in electrolyte. ACS Energy Lett. 4, 2111–2116 (2019).

    Article  CAS  Google Scholar 

  34. Nash, J. et al. Electrochemical nitrogen reduction reaction on noble metal catalysts in proton and hydroxide exchange membrane electrolyzers. J. Electrochem. Soc. 164, F1712–F1716 (2017).

    Article  CAS  Google Scholar 

  35. Dabundo, R. et al. The contamination of commercial 15N2 gas stocks with 15N–labeled nitrate and ammonium and consequences for nitrogen fixation measurements. PLoS One 9, e110335 (2014).

    Article  Google Scholar 

  36. Kim, K., Chen, Y., Han, J.-I., Yoon, H. C. & Li, W. Lithium-mediated ammonia synthesis from water and nitrogen: a membrane-free approach enabled by an immiscible aqueous/organic hybrid electrolyte system. Green. Chem. 21, 3839–3845 (2019).

    Article  CAS  Google Scholar 

  37. Chou, S.-S., Chung, J.-C., And, D.-F. & Hwang, D.-F. A high performance liquid chromatography method for determining nitrate and nitrite levels in vegetables. J. Food Drug Anal. 11, 11 (2003).

  38. Haynes, W. M. CRC Handbook of Chemistry and Physics (CRC, 2016).

  39. Watt, G. W. & Chrisp, J. D. Spectrophotometric method for determination of hydrazine. Anal. Chem. 24, 2006–2008 (1952).

    Article  CAS  Google Scholar 

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This research was partly supported by ARPA-E agency through REFUEL program (grant no. DE-AR0000812) and by Iowa Economic Development Authority (IEDA, grant no. AWD-019199). We are grateful to S. D. Cady, D. Jing, and B. W. Boote from Iowa State University for their generous assistance in NMR and material characterization. We also acknowledge fruitful discussions with J. Li, E. A. Smith, H. Lin, B. H. Shanks, R. C. Brown, J. L. Trettin (Iowa State University), K. Kim (University of Illinois at Urbana-Champaign) and G. Soloveichik (ARPA-E) on the electrosynthesis of ammonia. W. Li thanks his Bailey Research Career Development Award and Richard Seagrave Professorship. Y. Chen acknowledges his Catron Graduate Fellowship from Catron Center for Solar Energy Research at Iowa State University.

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Authors and Affiliations



W.L., S.G. and S.L. proposed the research and supervised the project. Y.C. performed material characterization. H.L. carried out HPLC measurements. Y.C. and N.H. set up the electrolytic cell system with the assistance from S.G. and S.L. and performed the electrochemical studies. Y.C., S.G., S.L. and W.L. co-wrote the paper. All authors discussed the results and commented on the manuscript.

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Correspondence to Stuart Licht, Shuang Gu or Wenzhen Li.

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Supplementary Tables 1–4, Figs. 1–8 and references.

Supplementary Data 1

Experimental Source Data for Supplementary Table 1 and Supplementary Figs. 2, 3 and 5–7.

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Chen, Y., Liu, H., Ha, N. et al. Revealing nitrogen-containing species in commercial catalysts used for ammonia electrosynthesis. Nat Catal 3, 1055–1061 (2020).

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