Non-aqueous gas diffusion electrodes for rapid ammonia synthesis from nitrogen and water-splitting-derived hydrogen

Abstract

Electrochemical transformations in non-aqueous solvents are important for synthetic and energy storage applications. Use of non-polar gaseous reactants such as nitrogen and hydrogen in non-aqueous solvents is limited by their low solubility and slow transport. Conventional gas diffusion electrodes improve the transport of gaseous species in aqueous electrolytes by facilitating efficient gas–liquid contacting in the vicinity of the electrode. Their use with non-aqueous solvents is hampered by the absence of hydrophobic repulsion between the liquid phase and carbon fibre support. Herein we report a method to overcome transport limitations in tetrahydrofuran using a stainless steel cloth-based support for ammonia synthesis paired with hydrogen oxidation. An ammonia partial current density of 8.8 ± 1.4 mA cm−2 and a Faradaic efficiency of 35 ± 6% are obtained using a lithium-mediated approach. Hydrogen oxidation current densities of up to 25 mA cm−2 are obtained in two non-aqueous solvents with near-unity Faradaic efficiency. The approach is then applied to produce ammonia from nitrogen and water-splitting-derived hydrogen.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Fig. 1: Kinetic and transport considerations for lithium-mediated nitrogen reduction.
Fig. 2: Structure of a GDE.
Fig. 3: Efficiency of the steel cloth-based GDEs for the HOR and NRR.
Fig. 4: Coupling of electrodes for a sustainable overall reaction.

Data availability

The data that support the plots in this paper and other findings of this study are available from the corresponding author on request.

References

  1. 1.

    Schiffer, Z. J. & Manthiram, K. Electrification and decarbonization of the chemical industry. Joule 1, 10–14 (2017).

    Article  Google Scholar 

  2. 2.

    Yan, M., Kawamata, Y. & Baran, P. S. Synthetic organic electrochemistry: calling all engineers. Angew. Chem. Int. Ed. 57, 4149–4155 (2018).

    CAS  Article  Google Scholar 

  3. 3.

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

    Article  Google Scholar 

  4. 4.

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

    CAS  Article  Google Scholar 

  5. 5.

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

    CAS  Article  Google Scholar 

  6. 6.

    Comer, B. M. et al. Prospects and challenges for solar fertilizers. Joule 3, 1578–1605 (2019).

    CAS  Article  Google Scholar 

  7. 7.

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

    CAS  Article  Google Scholar 

  8. 8.

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

    Article  Google Scholar 

  9. 9.

    Jiao, F. & Xu, B. Electrochemical ammonia synthesis and ammonia fuel cells. Adv. Mater. 31, 1805173 (2019).

    Article  Google Scholar 

  10. 10.

    Davis, S. J. et al. Net-zero emissions energy systems. Science 360, eaas9793 (2018).

    Article  Google Scholar 

  11. 11.

    Liu, X., Jiao, Y., Zheng, Y., Jaroniec, M. & Qiao, S.-Z. Building up a picture of the electrocatalytic nitrogen reduction activity of transition metal single-atom catalysts. J. Am. Chem. Soc. 141, 9664–9672 (2019).

    CAS  Article  Google Scholar 

  12. 12.

    Peters, B. K. et al. Scalable and safe synthetic organic electroreduction inspired by Li-ion battery chemistry. Science 363, 838–845 (2019).

    CAS  Article  Google Scholar 

  13. 13.

    Matthessen, R., Fransaer, J., Binnemans, K. & De Vos, D. E. Electrocarboxylation: towards sustainable and efficient synthesis of valuable carboxylic acids. Beilstein J. Org. Chem. 10, 2484–2500 (2014).

    Article  Google Scholar 

  14. 14.

    Möhle, S. et al. Modern electrochemical aspects for the synthesis of value-added organic products. Angew. Chem. Int. Ed. 57, 6018–6041 (2018).

    Article  Google Scholar 

  15. 15.

    McEnaney, J. M. et al. Ammonia synthesis from N2 and H2O using a lithium cycling electrification strategy at atmospheric pressure. Energy Environ. Sci. 10, 1621–1630 (2017).

    CAS  Article  Google Scholar 

  16. 16.

    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).

  17. 17.

    Kim, K. et al. Electrochemical synthesis of ammonia from water and nitrogen: a lithium-mediated approach using lithium-ion conducting glass ceramics. ChemSusChem 11, 120–124 (2018).

    CAS  Article  Google Scholar 

  18. 18.

    Kim, K. et al. Lithium-mediated ammonia electro-synthesis: effect of CsClO4 on lithium plating efficiency and ammonia synthesis. J. Electrochem. Soc. 165, F1027–F1031 (2018).

    CAS  Article  Google Scholar 

  19. 19.

    McEnaney, J. M. et al. Electro-thermochemical Li cycling for NH3 synthesis from N2 and H2O. US patent US20180029895A1 (2019).

  20. 20.

    Lazouski, N., Schiffer, Z. J., Williams, K. & Manthiram, K. Understanding continuous lithium-mediated electrochemical nitrogen reduction. Joule 3, 1127–1139 (2019).

    CAS  Article  Google Scholar 

  21. 21.

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

    CAS  Article  Google Scholar 

  22. 22.

    Tsuneto, A., Kudo, A. & Sakata, T. Lithium-mediated electrochemical reduction of high pressure N2 to NH3. J. Electroanal. Chem. 367, 183–188 (1994).

    CAS  Article  Google Scholar 

  23. 23.

    Schwalbe, J. A. et al. A combined theory‐experiment analysis of the surface species in lithium mediated NH3 electrosynthesis. ChemElectroChem 7, 1542–1549 (2020).

  24. 24.

    Singh, A. R. et al. Strategies toward selective electrochemical ammonia synthesis. ACS Catal. 9, 8316–8324 (2019).

    CAS  Article  Google Scholar 

  25. 25.

    Gibanel, F., López, M. C., Royo, F. M., Santafé, J. & Urieta, J. S. Solubility of nonpolar gases in tetrahydrofuran at 0 to 30 °C and 101.33 kPa partial pressure of gas. J. Solut. Chem. 22, 211–217 (1993).

    CAS  Article  Google Scholar 

  26. 26.

    Bard, A. J. & Faulkner, L. R. Electrochemical Methods. Fundamentals and Applications (John Wiley & Sons, 2001).

  27. 27.

    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).

    CAS  Article  Google Scholar 

  28. 28.

    Mathur, V. & Crawford, J. Fundamentals of gas diffusion layers in PEM fuel cells. Recent Trends Fuel Cell Sci. Technol. 400, 116–128 (2007).

    Article  Google Scholar 

  29. 29.

    Litster, S. & McLean, G. PEM fuel cell electrodes. J. Power Sources 130, 61–76 (2004).

    CAS  Article  Google Scholar 

  30. 30.

    Ripatti, D. S., Veltman, T. R. & Kanan, M. W. Carbon monoxide gas diffusion electrolysis that produces concentrated C2 products with high single-pass conversion. Joule 3, 240–256 (2018).

    Article  Google Scholar 

  31. 31.

    Ren, S. et al. Molecular electrocatalysts can mediate fast, selective CO2 reduction in a flow cell. Science 365, 367–369 (2019).

    CAS  Article  Google Scholar 

  32. 32.

    Higgins, D., Hahn, C., Xiang, C., Jaramillo, T. F. & Weber, A. Z. Gas-diffusion electrodes for carbon dioxide reduction: a new paradigm. ACS Energy Lett. 4, 317–324 (2019).

    CAS  Article  Google Scholar 

  33. 33.

    Burdyny, T. & Smith, W. A. CO2 Reduction on gas-diffusion electrodes and why catalytic performance must be assessed at commercially-relevant conditions. Energy Environ. Sci. 12, 1442–1453 (2019).

    CAS  Article  Google Scholar 

  34. 34.

    Weng, L. C., Bell, A. T. & Weber, A. Z. Modeling gas-diffusion electrodes for CO2 reduction. Phys. Chem. Chem. Phys. 20, 16973–16984 (2018).

    CAS  Article  Google Scholar 

  35. 35.

    Tran, C., Yang, X.-Q. & Qu, D. Investigation of the gas-diffusion-electrode used as lithium/air cathode in non-aqueous electrolyte and the importance of carbon material porosity. J. Power Sources 195, 2057–2063 (2010).

    CAS  Article  Google Scholar 

  36. 36.

    Balaish, M., Kraytsberg, A. & Ein-Eli, Y. Realization of an artificial three-phase reaction zone in a Li–air battery. ChemElectroChem 1, 90–94 (2014).

    Article  Google Scholar 

  37. 37.

    Gourdin, G., Xiao, N., McCulloch, W. & Wu, Y. Use of polarization curves and impedance analyses to optimize the ‘triple-phase boundary’ in K–O2 batteries. ACS Appl. Mater. Interfaces 11, 2925–2934 (2019).

    CAS  Article  Google Scholar 

  38. 38.

    Santamaria, A. D., Das, P. K., MacDonald, J. C. & Weber, A. Z. Liquid-water interactions with gas-diffusion-layer surfaces. J. Electrochem. Soc. 161, F1184–F1193 (2014).

    Article  Google Scholar 

  39. 39.

    Morgan, E. R., Manwell, J. F. & McGowan, J. G. Sustainable ammonia production from U.S. offshore wind farms: a techno-economic review. ACS Sustain. Chem. Eng. 5, 9554–9567 (2017).

    CAS  Article  Google Scholar 

  40. 40.

    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).

    CAS  Article  Google Scholar 

  41. 41.

    Kibsgaard, J., Nørskov, J. K. & Chorkendorff, I. The difficulty of proving electrochemical ammonia synthesis. ACS Energy Lett. 4, 2986–2988 (2019).

    CAS  Article  Google Scholar 

  42. 42.

    NREL Equipment Design and Cost Estimation for Small Modular Biomass Systems, Synthesis Gas Cleanup and Oxygen Separation Equipment Subcontract report (Nexant Inc., 2006); http://www.nrel.gov/docs/fy06osti/39946.pdf

  43. 43.

    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).

    CAS  Article  Google Scholar 

Download references

Acknowledgements

This material is based on work supported by the National Science Foundation under grant no. 1944007 and the MIT Energy Initiative (MITEI) seed fund. N.L. acknowledges support by the National Science Foundation Graduate Research Fellowship under grant no. 1122374. We thank M. Wolski of Daramic for providing us with polyporous separator samples.

Author information

Affiliations

Authors

Contributions

N.L. and K.M conceptualized the paper. N.L. was responsible for the methodology. N.L. and M.L.G. carried out the investigation. M.C. performed the validation. N.L. wrote the original draft of the manscript and K.W., N.L., M.C. and K.M. reviewed and edited its contents. K.M. supervised the work.

Corresponding author

Correspondence to Karthish Manthiram.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Scanning electron microscopy (SEM) images of stainless steel cloth electrodes.

A Zeiss-Merlin HR-SEM with an HE-SE2 detector was used to collect images. a, An image of a bare stainless steel cloth (SSC) (Supplementary Fig. 4). b, An image of a nickel-coated SSC (Supplementary Fig. 5).

Extended Data Fig. 2 Control experiments confirming nitrogen reduction to ammonia.

a, A comparison between the Faradaic efficiency toward ammonia when various gases are fed to the cell. When using N2 with different isotopic compositions, the ammonia yields are practically identical, which is a sign that N2 reduction is responsible for ammonia formation21. There is little to no ammonia formed when Ar is used as the feed gas and in the absence of current. Vertical error bars represent the uncertainty in Faradaic efficiency quantification of a single experiment. b, The amount of ammonia quantified in the base and acid traps used to clean the inlet gas, and the concentration of ammonia in a post-cell acid trap for comparison. c, Unscaled NMR spectra of electrolyte and acid trap solutions. When 14N2 is used as the feed gas, only a triplet from 14NH4+ is detected in both the trap and solution, while both 15NH4+ and 14NH4+ are detected when 15N2 is fed. ~92% of the NH4+ is 15NH4, which suggests some 14N2 contamination in the experiment, as the nominal isotopic content of the 15N2 is 98%. The peaks shift slightly due to differences in solvent composition (THF-water mixtures). The peak at ~6.87 is from butylated hydroxytoluene (BHT) found in the THF. The 25 mA experiments were performed by using a 3-compartment cell with a platinum foil anode, while the 20 mA experiments used a cell with no separator between electrolyte compartments and a Pt/SSC anode.

Supplementary information

Supplementary Information

Supplementary Methods, Figs. 1–25, Tables 1–5, discussion and references.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Lazouski, N., Chung, M., Williams, K. et al. Non-aqueous gas diffusion electrodes for rapid ammonia synthesis from nitrogen and water-splitting-derived hydrogen. Nat Catal 3, 463–469 (2020). https://doi.org/10.1038/s41929-020-0455-8

Download citation

Further reading