A half-wave rectified alternating current electrochemical method for uranium extraction from seawater


In total there is hundreds of times more uranium in sea water than on land, but extracting it for use in nuclear power generation is challenging due to its low concentration (3 ppb) and the high salinity background. Current approaches based on sorbent materials are limited due to their surface-based physicochemical adsorption nature. Here we use a half-wave rectified alternating current electrochemical (HW-ACE) method for uranium extraction from sea water based on an amidoxime-functionalized carbon electrode. The amidoxime functionalization enables surface specific binding to uranyl ions, while the electric field can migrate the ions to the electrode and induce electrodeposition of uranium compounds, forming charge-neutral species. Extraction is not limited by the electrode surface area, and the alternating manner of the applied voltage prevents unwanted cations from blocking the active sites and avoids water splitting. The HW-ACE method achieved a ninefold higher uranium extraction capacity (1,932 mg g−1) without saturation and fourfold faster kinetics than conventional physicochemical methods using uranium-spiked sea water.

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Figure 1: Schematics of physicochemical and HW-ACE extraction.
Figure 2: C-Ami electrode characterization and visualization of the extraction difference between the physicochemical and HW-ACE methods.
Figure 3: HW-ACE uranium extraction performance using spiked real sea water.
Figure 4: HW-ACE extraction mechanism study and extracted uranium species analysis.
Figure 5: Unspiked real sea water U extraction.


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We acknowledge the DOE Office of Nuclear Energy for funding. We acknowledge the Stanford facilities, SNSF and EMF, for characterization. We acknowledge C. Hitzman for his help in NanoSIMS characterization.

Author information




C.L. and Y.C. conceived the concept. C.L. synthesized the C-Ami electrodes, conducted the electrode characterization and measured the performances. P.-C.H. helped with the FTIR and XRD characterization. J.X. helped with the Raman characterization. J.Z. and H.W. helped with the XPS characterization. T.W. helped with performance measurements. W.L. helped with patterned electrode fabrication. S.C. and Y.C supervised the project. C.L., S.C. and Y.C. analysed the data and co-wrote the paper. All authors discussed the whole paper.

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Correspondence to Yi Cui.

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The authors declare no competing financial interests.

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Supplementary Figures 1–16, Supplementary Discussion, Supplementary References (PDF 1217 kb)

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Liu, C., Hsu, PC., Xie, J. et al. A half-wave rectified alternating current electrochemical method for uranium extraction from seawater. Nat Energy 2, 17007 (2017). https://doi.org/10.1038/nenergy.2017.7

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