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Electrosynthesis of urea on cadmium-modified iron oxide

Nature Synthesis (2026)Cite this article

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Abstract

Electrosynthesis of urea at practical relevant current densities remains challenging due to competing side reactions, particularly at the elevated overpotentials required to sustain high currents. Here we propose a catalyst design strategy for selective urea production at practical current densities, emphasizing materials with low activity for competing CO2 reduction and hydrogen evolution, and high activity for nitrate activation under high overpotentials. We develop a cadmium-modified Fe2O3 (Cd–Fe2O3) catalyst composite, achieving a high urea partial current density of approximately 140 mA cm−2 at a modest cathodic potential of −0.5 V versus reversible hydrogen electrode, with an appreciable Faradaic efficiency of 52%. Through detailed kinetics analysis, in situ spectroscopic investigations and density functional theory calculations, we reveal that Cd incorporation into Fe2O3 substantially weakens *CO adsorption by altering the electronic structure and preserving oxidized Fe species. This modification suppresses undesired Volmer-type hydrogen adsorption while promoting *CO2NH2 intermediate protonation, enhancing urea formation. As a result, competing hydrogen evolution is effectively suppressed, and high urea selectivity is maintained at elevated current densities on Cd–Fe2O3.

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Fig. 1: Performance landscape and techno-economic determinants of electrochemical urea synthesis.
Fig. 2: Competitive reaction pathways governing electrochemical urea synthesis.
Fig. 3: Influence of CO2 on HER kinetics and surface CO binding on Fe2O3 catalysts.
Fig. 4: Structural characterization of Fe2O3 and Cd–Fe2O3.
Fig. 5: Electrochemical performance, kinetic parameters and operando spectroscopic insights of urea electrosynthesis on Cd–Fe2O3.
Fig. 6: Density functional theory calculations of urea formation on pristine Fe and Cd–Fe catalysts.

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The data that support the findings of this study are available in Supplementary Information. Source data are provided with this paper.

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Acknowledgements

We acknowledge the Ministry of Education Singapore for their financial support, through the grant of T2EP50124-0012. We also acknowledge the support of the National Research Foundation (NRF) Singapore, under the NRF Fellowship (NRF-NRFF13-2021-0007) and CRP (NRF-CRP27-2021-0004), as well as the support from the Centre for Hydrogen Innovations at the NUS (CHI-P2024-03). P.O. and Y.L. acknowledge the use of Singapore National Supercomputing Centre high-performance computing facilities, consulting support and/or training services as part of this research. As a National Research Infrastructure funded by the NRF (https://www.nscc.sg), P.O. also acknowledges the support from the National University of Singapore Presidential Young Professorship Start-Up Grant (A-0010024-00-00). We also thank S. Xi at Singapore Synchrotron Light Source for his assistance with XAS characterization.

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Author notes

  1. These authors contributed equally: Bihao Hu, Yan Liu, Yifan Zhou.

Authors and Affiliations

  1. Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore

    Bihao Hu, Yifan Zhou, Siming Yang, Zhihao Wang, Harshini Shankar & Lei Wang

  2. Department of Chemistry, National University of Singapore, Singapore, Singapore

    Yan Liu & Pengfei Ou

  3. Department of Chemical Engineering, Tsinghua University, Beijing, China

    Zhihao Wang, Yi Shen Tew & Xiaonan Wang

  4. Centre for Hydrogen Innovations, National University of Singapore, Singapore, Singapore

    Lei Wang

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Contributions

L.W. supervised the project. L.W. and B.H. conceived the idea. B.H. and Y.Z. designed and performed the experiments. B.H. and Y.Z. conducted the TEA under L.W.’s supervision. Z.W., Y.S.T. and B.H. conducted the large language model under X.W.’s supervision. Y.L. completed the theoretical calculations under P.O.’s supervision. L.W., P.O., B.H., Y.L., Y.Z., S.Y. and H.S. contributed to the data interpretation and wrote the paper. All the authors contributed to the revision of the paper.

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Correspondence to Pengfei Ou or Lei Wang.

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Nature Synthesis thanks Cao-Thang Dinh, Liangzhi Kou and Fusheng Li for their contribution to the peer review of this work. Primary Handling Editor: Alexandra Groves, in collaboration with the Nature Synthesis team.

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Hu, B., Liu, Y., Zhou, Y. et al. Electrosynthesis of urea on cadmium-modified iron oxide. Nat. Synth (2026). https://doi.org/10.1038/s44160-026-00995-9

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