Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Coupling N2 and CO2 in H2O to synthesize urea under ambient conditions


The use of nitrogen fertilizers has been estimated to have supported 27% of the world’s population over the past century. Urea (CO(NH2)2) is conventionally synthesized through two consecutive industrial processes, N2 + H2 → NH3 followed by NH3 + CO2 → urea. Both reactions operate under harsh conditions and consume more than 2% of the world’s energy. Urea synthesis consumes approximately 80% of the NH3 produced globally. Here we directly coupled N2 and CO2 in H2O to produce urea under ambient conditions. The process was carried out using an electrocatalyst consisting of PdCu alloy nanoparticles on TiO2 nanosheets. This coupling reaction occurs through the formation of C–N bonds via the thermodynamically spontaneous reaction between *N=N* and CO. Products were identified and quantified using isotope labelling and the mechanism investigated using isotope-labelled operando synchrotron-radiation Fourier transform infrared spectroscopy. A high rate of urea formation of 3.36 mmol g–1 h–1 and corresponding Faradic efficiency of 8.92% were measured at –0.4 V versus reversible hydrogen electrode.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Morphology and high-resolution XPS spectra of catalysts.
Fig. 2: Evaluation of the electrocatalytic performance of Pd1Cu1/TiO2-400 in a flow cell.
Fig. 3: Sorption of gaseous molecules on catalysts.
Fig. 4: Isotope-labelling operando SR-FTIR spectroscopy measurement results.
Fig. 5: Theoretical calculation results for urea synthesis.

Data availability

All data generated or analysed during this study are included in this Article (and its Supplementary Information). Data for Figs. 1–5 are available as source data with this paper.

Code availability

The computational codes used in the current work are available from the corresponding author on reasonable request.


  1. 1.

    Erisman, J. W., Sutton, M. A., Galloway, J., Klimont, Z. & Winiwarter, W. How a century of ammonia synthesis changed the world. Nat. Geosci. 1, 636–639 (2008).

    CAS  Google Scholar 

  2. 2.

    Barzagli, F., Mani, F. & Peruzzini, M. From greenhouse gas to feedstock: formation of ammonium carbamate from CO2 and NH3 in organic solvents and its catalytic conversion into urea under mild conditions. Green Chem. 13, 1267–1274 (2011).

    CAS  Google Scholar 

  3. 3.

    Pérez-Fortes, M., Bocin-Dumitriu, A. & Tzimas, E. CO2 utilization pathways: techno-economic assessment and market opportunities. Energy Procedia 63, 7968–7975 (2014).

    Google Scholar 

  4. 4.

    Giddey, S., Badwal, S. P. S. & Kulkarni, A. Review of electrochemical ammonia production technologies and materials. Int. J. Hydrog. Energy 38, 14576–14594 (2013).

    CAS  Google Scholar 

  5. 5.

    Service, R. F. Chemistry. New recipe produces ammonia from air, water, and sunlight. Science 345, 610 (2014).

    CAS  PubMed  Google Scholar 

  6. 6.

    Chen, C. et al. B–N pairs enriched defective carbon nanosheets for ammonia synthesis with high efficiency. Small 15, 1805029 (2019).

    Google Scholar 

  7. 7.

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

    CAS  PubMed  Google Scholar 

  8. 8.

    Shi, M. M. et al. Au sub-nanoclusters on TiO2 toward highly efficient and selective electrocatalyst for N2 conversion to NH3 at ambient conditions. Adv. Mater. 29, 1606550 (2017).

    Google Scholar 

  9. 9.

    Bao, D. et al. Electrochemical reduction of N2 under ambient conditions for artificial N2 fixation and renewable energy storage using N2/NH3 cycle. Adv. Mater. 29, 1604799 (2017).

    Google Scholar 

  10. 10.

    Chen, G. F. et al. Ammonia electrosynthesis with high selectivity under ambient conditions via a Li+ incorporation strategy. J. Am. Chem. Soc. 139, 9771–9774 (2017).

    CAS  PubMed  Google Scholar 

  11. 11.

    Li, S. J. et al. Amorphizing of Au nanoparticles by CeOx–RGO hybrid support towards highly efficient electrocatalyst for N2 reduction under ambient conditions. Adv. Mater. 29, 1700001 (2017).

    Google Scholar 

  12. 12.

    Chen, S. et al. Electrocatalytic synthesis of ammonia at room temperature and atmospheric pressure from water and nitrogen on a carbon-nanotube-based electrocatalyst. Angew. Chem. Int. Ed. 56, 2699–2703 (2017).

    CAS  Google Scholar 

  13. 13.

    Lan, R., Irvine, J. T. & Tao, S. Synthesis of ammonia directly from air and water at ambient temperature and pressure. Sci. Rep. 3, 1145 (2013).

    PubMed  PubMed Central  Google Scholar 

  14. 14.

    van der Ham, C. J., Koper, M. T. & Hetterscheid, D. G. Challenges in reduction of dinitrogen by proton and electron transfer. Chem. Soc. Rev. 43, 5183–5191 (2014).

    PubMed  Google Scholar 

  15. 15.

    Guo, C., Ran, J., Vasileff, A. & Qiao, S. Z. Rational design of electrocatalysts and photo(electro)catalysts for nitrogen reduction to ammonia (NH3) under ambient conditions. Energy Environ. Sci. 11, 45–56 (2018).

    CAS  Google Scholar 

  16. 16.

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

    Google Scholar 

  17. 17.

    Li, H., Shang, J., Ai, Z. & Zhang, L. Efficient visible light nitrogen fixation with BiOBr nanosheets of oxygen vacancies on the exposed {001} facets. J. Am. Chem. Soc. 137, 6393–6399 (2015).

    CAS  PubMed  Google Scholar 

  18. 18.

    Wang, S. et al. Light-switchable oxygen vacancies in ultrafine Bi5O7Br nanotubes for boosting solar-driven nitrogen fixation in pure water. Adv. Mater. 29, 1701774 (2017).

    Google Scholar 

  19. 19.

    Zheng, J. et al. Photoelectrochemical synthesis of ammonia on the aerophilic-hydrophilic heterostructure with 37.8% efficiency. Chem 5, 617–633 (2019).

    CAS  Google Scholar 

  20. 20.

    Wang, J. et al. Ambient ammonia synthesis via palladium-catalyzed electrohydrogenation of dinitrogen at low overpotential. Nat. Commun. 9, 1795 (2018).

    PubMed  PubMed Central  Google Scholar 

  21. 21.

    Yao, Y., Zhu, S., Wang, H., Li, H. & Shao, M. A spectroscopic study on the nitrogen electrochemical reduction reaction on gold and platinum surfaces. J. Am. Chem. Soc. 140, 1496–1501 (2018).

    CAS  PubMed  Google Scholar 

  22. 22.

    Geng, Z. et al. Achieving a record-high yield rate of 120.9 for N2 electrochemical reduction over Ru single-atom catalysts. Adv. Mater. 30, 1803498 (2018).

    Google Scholar 

  23. 23.

    Yu, X. et al. Boron-doped graphene for electrocatalytic N2 reduction. Joule 2, 1610–1622 (2018).

    CAS  Google Scholar 

  24. 24.

    Inagaki, F., Matsumoto, C., Iwata, T. & Mukai, C. CO2-selective absorbents in air: reverse lipid bilayer structure forming neutral carbamic acid in water without hydration. J. Am. Chem. Soc. 139, 4639–4642 (2017).

    CAS  PubMed  Google Scholar 

  25. 25.

    McDonald, T. M., D’Alessandro, D. M., Krishna, R. & Long, J. R. Enhanced carbon dioxide capture upon incorporation of N,N′-dimethylethylenediamine in the metal–organic framework CuBTTri. Chem. Sci. 2, 2022–2028 (2011).

    CAS  Google Scholar 

  26. 26.

    Flaig, R. W. et al. The chemistry of CO2 capture in an amine-functionalized metal–organic framework under dry and humid conditions. J. Am. Chem. Soc. 139, 12125–12128 (2017).

    CAS  PubMed  Google Scholar 

  27. 27.

    Planas, N. et al. The mechanism of carbon dioxide adsorption in an alkylamine-functionalized metal–organic framework. J. Am. Chem. Soc. 135, 7402–7405 (2013).

    CAS  PubMed  Google Scholar 

  28. 28.

    Zhu, D. D., Liu, J. L. & Qiao, S. Z. Recent advances in inorganic heterogeneous electrocatalysts for reduction of carbon dioxide. Adv. Mater. 28, 3423–3452 (2016).

    CAS  PubMed  Google Scholar 

  29. 29.

    Jouny, M., Luc, W. & Jiao, F. High-rate electroreduction of carbon monoxide to multi-carbon products. Nat. Catal. 1, 748–755 (2018).

    CAS  Google Scholar 

  30. 30.

    Luc, W. et al. Two-dimensional copper nanosheets for electrochemical reduction of carbon monoxide to acetate. Nat. Catal. 2, 423–430 (2019).

    CAS  Google Scholar 

  31. 31.

    Jouny, M., Hutchings, G. S. & Jiao, F. Carbon monoxide electroreduction as an emerging platform for carbon utilization. Nat. Catal. 2, 1062–1070 (2019).

    CAS  Google Scholar 

  32. 32.

    Jouny, M. et al. Formation of carbon–nitrogen bonds in carbon monoxide electrolysis. Nat. Chem. 11, 846–851 (2019).

    CAS  PubMed  Google Scholar 

  33. 33.

    Comer, B. M. et al. The role of adventitious carbon in photo-catalytic nitrogen fixation by titania. J. Am. Chem. Soc. 140, 15157–15160 (2018).

    CAS  PubMed  Google Scholar 

  34. 34.

    Srinivas, B., Kumari, V. D., Sadanandam, G., Subrahmanyam, C. H. M. & De, B. R. Photocatalytic synthesis of urea from in situ generated ammonia and carbon dioxide. Photochem. Photobiol. 88, 233–241 (2012).

    CAS  PubMed  Google Scholar 

  35. 35.

    Wang, J. et al. A bifunctional catalyst for efficient dehydrogenation and electro-oxidation of hydrazine. J. Mater. Chem. A 6, 18050–18056 (2018).

    CAS  Google Scholar 

  36. 36.

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

    CAS  Google Scholar 

  37. 37.

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

    CAS  Google Scholar 

  38. 38.

    Medford, A. J. et al. Assessing the reliability of calculated catalytic ammonia synthesis rates. Science 345, 197–200 (2014).

    CAS  PubMed  Google Scholar 

  39. 39.

    Duyar, M. S. et al. A highly active molybdenum phosphide catalyst for methanol synthesis from CO and CO2. Angew. Chem. Int. Ed. 130, 15265–15270 (2018).

    Google Scholar 

  40. 40.

    Andersen, M. et al. Scaling-relation-based analysis of bifunctional catalysis: the case for homogeneous bimetallic alloys. ACS Catal. 7, 3960–3967 (2017).

    CAS  Google Scholar 

  41. 41.

    Yan, D., Li, H., Chen, C., Zou, Y. & Wang, S. Defect engineering strategies for nitrogen reduction reactions under ambient conditions. Small Methods 3, 1800331 (2018).

    Google Scholar 

  42. 42.

    Wan, J. et al. Defect effects on TiO2 nanosheets: stabilizing single atomic site Au and promoting catalytic properties. Adv. Mater. 30, 1705369 (2018).

    Google Scholar 

  43. 43.

    Qiu, Y. et al. BCC-phased PdCu alloy as a highly active electrocatalyst for hydrogen oxidation in alkaline electrolytes. J. Am. Chem. Soc. 140, 16580–16588 (2018).

    PubMed  Google Scholar 

  44. 44.

    Shi, M. M. et al. Anchoring PdCu amorphous nanocluster on graphene for electrochemical reduction of N2 to NH3 under ambient conditions in aqueous solution. Adv. Energy Mater. 8, 1800124 (2018).

    Google Scholar 

  45. 45.

    Rahmatullah, M. & Boyde, T. R. C. Improvements in the determination of urea using diacetyl monoxime; methods with and without deproteinisation. Clin. Chim. Acta 107, 3–9 (1980).

    CAS  PubMed  Google Scholar 

  46. 46.

    Ma, S. et al. Electroreduction of carbon dioxide to hydrocarbons using bimetallic Cu-Pd catalysts with different mixing patterns. J. Am. Chem. Soc. 139, 47–50 (2016).

    PubMed  Google Scholar 

  47. 47.

    Hoang, T. T. H. et al. Nanoporous copper-silver alloys by additive-controlled electrodeposition for the selective electroreduction of CO2 to ethylene and ethanol. J. Am. Chem. Soc. 140, 5791–5797 (2018).

    CAS  PubMed  Google Scholar 

  48. 48.

    Ma, S., Lan, Y., Perez, G. M. J., Moniri, S. & Kenis, P. J. A. Silver supported on titania as an active catalyst for electrochemical carbon dioxide reduction. ChemSusChem 7, 866–874 (2014).

    CAS  PubMed  Google Scholar 

  49. 49.

    Cook, R. L. & Sammells, A. F. Ambient temperature gas phase electrochemical nitrogen reduction to ammonia at ruthenium/solid polymer electrolyte interface. Catal. Lett. 1, 345–349 (1988).

    CAS  Google Scholar 

  50. 50.

    Billy, J. T. & Co, A. C. Experimental parameters influencing hydrocarbon selectivity during the electrochemical conversion of CO2. ACS Catal. 7, 8467–8479 (2017).

    CAS  Google Scholar 

  51. 51.

    Albo, J. & Irabien, A. Cu2O-loaded gas diffusion electrodes for the continuous electrochemical reduction of CO2 to methanol. J. Catal. 343, 232–239 (2016).

    CAS  Google Scholar 

  52. 52.

    Wang, H. et al. Selective electrochemical reduction of nitrogen to ammonia by adjusting the three-phase interface. Research 2019, 1401209 (2019).

    PubMed Central  Google Scholar 

  53. 53.

    Hao, Y. et al. Promoting nitrogen electroreduction to ammonia with bismuth nanocrystals and potassium cations in water. Nat. Catal. 2, 448–456 (2019).

    Google Scholar 

  54. 54.

    Cheng, W. R. et al. Lattice-strained metal–organic-framework arrays for bifunctional oxygen electrocatalysis. Nat. Energy 4, 115–122 (2019).

    CAS  Google Scholar 

  55. 55.

    Coleman, M. M., Lee, K. H., Skrovanek, D. J. & Painter, P. C. Hydrogen bonding in polymers. 4. Infrared temperature studies of a simple polyurethane. Macromolecules 19, 2149–2157 (1986).

    CAS  Google Scholar 

  56. 56.

    Manivannan, M. & Rajendran, S. Investigation of inhibitive action of urea-Zn2+ system in the corrosion control of carbon steel in sea water. Int. J. Engr. Sci. Technol. 3, 8048–8060 (2011).

    Google Scholar 

  57. 57.

    Buong, W. C., Nor, A. I., Wan, M. Z. W. Y. & Mohd, Z. H. Poly(lactic acid)/poly(ethylene glycol) polymer nanocomposites: effects of graphene nanoplatelets. Polymers 6, 93–104 (2014).

    Google Scholar 

  58. 58.

    Daramola, M. O., Nicola, W. & Jacob, M. N. Effect of the presence of water-soluble amines on the carbon dioxide (CO2) adsorption capacity of amine-grafted poly-succinimide (PSI) adsorbent during CO2 capture. Energy Procedia 86, 90–105 (2016).

    Google Scholar 

  59. 59.

    Nørskov, J. K. et al. Origin of the overpotential for oxygen reduction at a fuel-cell cathode. J. Phys. Chem. B 108, 17886–17892 (2004).

    Google Scholar 

  60. 60.

    Honkala, K. et al. Ammonia synthesis from first-principles calculations. Science 307, 555–558 (2005).

    CAS  PubMed  Google Scholar 

  61. 61.

    Duan, H. et al. Molecular nitrogen promotes catalytic hydrodeoxygenation. Nat. Catal. 2, 1078–1087 (2019).

    CAS  Google Scholar 

  62. 62.

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

    CAS  Google Scholar 

  63. 63.

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

    CAS  PubMed  Google Scholar 

  64. 64.

    Kresse, G. & Furthmüller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169 (1996).

    CAS  Google Scholar 

  65. 65.

    Blöchl, P. E. Projector augmented-wave method. Phys. Rev. B 24, 17953 (1994).

    Google Scholar 

  66. 66.

    Perdew, J. P., Burke, K. & Ernzerhof, M. Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865 (1996).

    CAS  Google Scholar 

  67. 67.

    Henkelman, G., Uberuaga, B. P. & Jónsson, H. A climbing image nudged elastic band method for finding saddle points and minimum energy paths. J. Chem. Phys. 113, 9901–9904 (2000).

    CAS  Google Scholar 

  68. 68.

    Computational Chemistry Comparison and Benchmark Database (NIST, accessed 2016);

Download references


We thank the National Natural Science Foundation of China (grant no. 21573066, 21825201, U1932212, U19A2017) and ARC DP170102320.

Author information




S.W. conceived the project. C.C. and Y.Z. carried out most of the experiments and co-wrote the manuscript. X.Z., X.W., Y.L. and J.C. performed the theoretical calculations. Q.L., H.S., X.Z. and W.C. carried out the isotope-labelling operando SR-FTIR measurements. L.Z., L.T., H.L., Q.L., S.D., T.L., D.Y. and C.X. conducted part of the synthesis of catalysts and characterizations. Y.Z., Y.W., R.C. and J.H. analysed the data. H.L., J.L., J.C. and M.D. performed the partial characterizations of materials. K.C. and C.L. performed the collection and analysis of NMR spectra. All authors discussed the results and commented on the manuscript.

Corresponding authors

Correspondence to Yafei Li or Jun Cheng or Qinghua Liu or Jun Chen or Shuangyin Wang.

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.

Supplementary information

Supplementary Information

Supplementary Figs. 1–43, Tables 13 and refs. 1–4.

Source data

Source Data Fig. 1

High-resolution XPS spectra of catalysts.

Source Data Fig. 2

Evaluation of the electrocatalytic performance of Pd1Cu1/TiO2-400 in a flow cell.

Source Data Fig. 3

Sorption of gaseous molecules on catalysts.

Source Data Fig. 4

Isotope-labelling operando SR-FTIR spectroscopy measurement results.

Source Data Fig. 5

Theoretical calculation results for urea synthesis.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Chen, C., Zhu, X., Wen, X. et al. Coupling N2 and CO2 in H2O to synthesize urea under ambient conditions. Nat. Chem. 12, 717–724 (2020).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing