Ion-Current Rectification in Nanopores and Nanotubes with Broken Symmetry


  • Z. S. Siwy

    1. Department of Physics and Astronomy, University of California, Irvine, 2182 Frederick Reines Hall, Irvine, CA 92697, USA
    2. Department of Chemistry, Silesian University of Technology, Strzody, PL-944-100 Gliwice, Poland
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  • Irradiation with swift heavy ions was performed at the GSI, Darmstadt, Germany. Discussions with members of the Department of Materials Research of GSI are acknowledged. I am very grateful for many discussions with Prof. Charles R. Martin, for wonderful hospitality, and the scientific milieu of his group. Help from Dr. Pavel Apel, Prof. Andrzej Fulinski, and Dr. Ilona Kosinska is also gratefully acknowledged.


This article focuses on ion transport through nanoporous systems with special emphasis on rectification phenomena. The effect of ion-current rectification is observed as asymmetric current–voltage (I–V) curves, with the current recorded for one voltage polarity higher than the current recorded for the same absolute value of voltage of opposite polarity. This diode-like I–V curve indicates that there is a preferential direction for ion flow. Experimental evidence that ion-current rectification is inherent to asymmetric, e.g., tapered, nanoporous systems with excess surface charge is provided and discussed. The fabrication and operation of asymmetric polymer nanopores, gold nanotubes, glass nanocapillaries, and silicon nanopores are presented. The possibility of tuning the direction and extent of rectification is discussed in detail. Theoretical models that have been developed to explain the ion-current rectification effect are also presented.