DOE OSTI · 3024374
A nanoporous capacitive electrochemical ratchet for continuous ion separations
Abstract
Directed ion transport in liquid electrolyte solutions underlies many phenomena in natural and industrial settings. While nature has evolved structures that drive continuous ion flow without Faradaic redox reactions, establishing this process in synthetic systems has been challenging. Here, in this study, we report an ion pump that drives aqueous ions against a force using a capacitive ratchet mechanism independent of redox reactions. Modulation of an electric potential between thin metallic layers on either face of a nanoporous alumina wafer immersed in solution results in persistent voltages and ionic currents. This occurs due to the nonlinear capacitive nature of electric double layers, whose repeated charging and discharging sustains a continuous ion flux. Using this approach, we demonstrate ratchet-driven electrodialysis that reaches a 50% decrease in the conductivity of the solution in a dilution cell. These ratchet-based ion pumps can enable continuous desalination and selective ion separation using an electrically powered device with no moving parts.
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Kautz, Rylan [University of California, Irvine, CA (United States)], Herman, Alon [Tel Aviv University (Israel)], Heffernan, Ethan J. [University of California, Irvine, CA (United States)], Shushan Alshochat, Keren [Tel Aviv University (Israel)] (ORCID:0009000667433806), Grossman, Eden [Tel Aviv University (Israel)] (ORCID:0009000175664894), Saxena, Rahul [Tel Aviv University (Israel)] (ORCID:0009000984090587), Muñetón, Camila [Tel Aviv University (Israel); University of Massachusetts, Boston, MA (United States)], Larson, David [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Ager III, Joel W. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of California, Berkeley, CA (United States)] (ORCID:0000000193349751), Toma, Francesca M. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Helmholtz-Zentrum Hereon, Teltow (Germany); Helmut Schmidt University, Hamburg (Germany)] (ORCID:0000000323320798), Ardo, Shane [University of California, Irvine, CA (United States)] (ORCID:0000000171626826), Segev, Gideon [Tel Aviv University (Israel)] (ORCID:0000000261753458). 2026-03-13. A nanoporous capacitive electrochemical ratchet for continuous ion separations. https://doi.org/10.1038/s41563-026-02511-y
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