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Electrosynthesis of pure urea from pretreated flue gas in a proton-limited environment established in a porous solid-state electrolyte electrolyser

Nature Nanotechnology volume 20, pages 907–913 (2025)Cite this article

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Abstract

The electrosynthesis of pure urea via the co-reduction of CO2 and N2 remains challenging. Here we show that a proton-limited environment established in an electrolyser equipped with porous solid-state electrolyte, devoid of an aqueous electrolyte, can suppress the hydrogen evolution reaction and excessive hydrogenation of N2 to ammonia. This can instead be conducive to the C–N coupling of *CO2 with *NHNH (the intermediate from the semi-hydrogenation of N2), thereby facilitating the production of urea. By using nanosheets of an ultrathin two-dimensional metal–azolate framework with cyclic heterotrimetal clusters as catalyst, the Faradaic efficiency of urea production from pretreated flue gas (which contains mainly 85% N2 and 15% CO2) is as high as 65.5%, and no ammonia and other liquid products were generated. At a low cell voltage of 2.0 V, the current can reach 100 mA, and the urea production rate is as high as 5.07 g gcat−1 h−1 or 84.4 mmol gcat−1 h−1. Notably, it can continuously produce 6.2 wt% pure urea aqueous solution for at least 30 h, and about 1.24 g pure urea solid was obtained. The use of pretreated flue gas as a direct feedstock significantly reduces input costs, and the high reaction rate and selectivity contribute to a reduction in system scale and operational costs.

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Fig. 1: Characterization of MAF-201.
Fig. 2: Electrochemical performances for urea electrosynthesis.
Fig. 3: Isotopic labelling experiments and stability test of MAF-201.
Fig. 4: Mechanism study.

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The data supporting the finding of the study are available in the article and its Supplementary Information. Source data are provided with this paper.

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Acknowledgements

This work was supported by the National Key R&D Program of China (grant no. 2024YFF0506100 to P.-Q.L.), NSFC (grant nos. 22090061 and 22488101 to X.-M.C., grant no. 22371304 to P.-Q.L.), the Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province (grant no. STKJ2023078 to X.-M.C. and P.-Q.L.), Fundamental Research Funds for the Central Universities, Sun Yat-Sen University (grant no. 24lgzy006 to P.-Q.L.), and the Guangzhou Science and Technology Program (grant no. SL2023A04J01767 to P.-Q.L.).

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Author notes

  1. These authors contributed equally: Yan-Chen Liu, Jia-Run Huang.

Authors and Affiliations

  1. MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, GBRCE for Functional Molecular Engineering, School of Chemistry, IGCME, Sun Yat-Sen University, Guangzhou, China

    Yan-Chen Liu, Jia-Run Huang, Hao-Lin Zhu, Xiao-Feng Qiu, Xiao-Ming Chen & Pei-Qin Liao

  2. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China

    Can Yu

  3. Chemistry and Chemical Engineering Guangdong Laboratory, Shantou, China

    Xiao-Ming Chen

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Contributions

P.-Q.L. designed the research. Y.-C.L. performed the syntheses and measurements. H.-L.Z. and X.-F.Q. assisted with the measurements. J.-R.H. performed the PDFT calculations. C.Y. performed the X-ray absorption spectroscopy measurements. Y.-C.L., J.-R.H., P.-Q.L. and X.-M.C. wrote the paper.

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Correspondence to Pei-Qin Liao.

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Nature Nanotechnology thanks Lin Guo, Shuangyin Wang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Liu, YC., Huang, JR., Zhu, HL. et al. Electrosynthesis of pure urea from pretreated flue gas in a proton-limited environment established in a porous solid-state electrolyte electrolyser. Nat. Nanotechnol. 20, 907–913 (2025). https://doi.org/10.1038/s41565-025-01914-3

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