Abstract
Synthetic nitrogen fertilizer such as urea has been key to increasing crop productivity and feeding a growing population. However, the conventional urea production relies on energy-intensive processes, consuming approximately 2% of annual global energy. Here, we report on a more-sustainable electrocatalytic approach that allows for direct and selective synthesis of urea from nitrate and carbon dioxide with an indium hydroxide catalyst at ambient conditions. Remarkably, Faradaic efficiency, nitrogen selectivity and carbon selectivity reach 53.4%, 82.9% and ~100%, respectively. The engineered surface semiconducting behaviour of the catalyst is found to suppress hydrogen evolution reaction. The key step of C–N coupling initiates through the reaction between *NO2 and *CO2 intermediates owing to the low energy barrier on {100} facets. This work suggests an appealing route of urea production and provides deep insight into the underlying chemistry of C–N coupling reaction that could guide sustainable synthesis of other indispensable chemicals.
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Data availability
All data that support the findings in this paper are available within the article and its Supplementary Information. Source data are available from the corresponding author upon reasonable request.
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Acknowledgements
Q.Y. acknowledges funding support from Singapore MOE AcRF Tier 1 grant no. 2020-T1-001-031, Tier 2 grant no. 2017-T2-2-069 and Singapore A*STAR project A19D9a0096. G.Y. acknowledges funding support from the US Department of Energy (grant number: DE-SC0019019) and Welch Foundation Award F-1861. S.L. acknowledges financial support from the Academic Research Fund Tier 1 (RG8/20), Tier 1 (RG104/18) and computing resources from the National Supercomputing Centre Singapore. This work is also supported by the Users with Excellence programme of Hefei Science Center of CAS(2020HSC-UE003). We greatly thank the Facility for Analysis, Characterization, Testing and Simulation (FACTS) of Nanyang Technological University, Singapore, for using their TEM, SEM and XRD equipment. We acknowledge NTU Center of High Field NMR Spectroscopy and Imaging. We also thank the National Synchrotron Radiation Laboratory for help in characterizations.
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G.Y. and Q.Y. conceived and directed the project. C. Lv carried out key experiments and wrote the manuscript. L.Z. and S.L. performed theoretical calculations. H.L. and L.S. conducted operando SR-FTIR measurements. C.Y. carried out the design of catalysts. M.C., Y.K., J.L., C. Lee and D.L. conducted part of the characterizations. C. Lv, L.Z., Z.F., Q.Y., G.Y., G.C., L.S. and S.L. analysed the data. All authors discussed the results and commented on the manuscript.
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Lv, C., Zhong, L., Liu, H. et al. Selective electrocatalytic synthesis of urea with nitrate and carbon dioxide. Nat Sustain 4, 868–876 (2021). https://doi.org/10.1038/s41893-021-00741-3
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DOI: https://doi.org/10.1038/s41893-021-00741-3
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