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arXiv · 1508.06494

Measuring the Proton Selectivity of Graphene Membranes

Michael I. Walker·Philipp Braeuninger-Weimar·Robert S. Weatherup·Stephan Hofmann·Ulrich F. Keyser
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Abstract

By systematically studying the proton selectivity of free-standing graphene membranes in aqueous solutions we demonstrate that protons are transported by passing through defects. We study the current-voltage characteristics of single-layer graphene grown by chemical vapour deposition (CVD) when a concentration gradient of HCl exists across it. Our measurements can unambiguously determine that H+ ions are responsible for the selective part of the ionic current. By comparing the observed reversal potentials with positive and negative controls we demonstrate that the as-grown graphene is only weakly selective for protons. We use atomic layer deposition to block most of the defects in our CVD graphene. Our results show that a reduction in defect size decreases the ionic current but increases proton selectivity.

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Michael I. Walker, Philipp Braeuninger-Weimar, Robert S. Weatherup, Stephan Hofmann, Ulrich F. Keyser. 2015-08-26. Measuring the Proton Selectivity of Graphene Membranes. https://doi.org/10.1063/1.4936335

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