Measuring the proton selectivity of graphene membranes

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 c...

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Bibliographic Details
Published in:Applied physics letters 2015-11, Vol.107 (21)
Main Authors: Walker, Michael I., Braeuninger-Weimer, Philipp, Weatherup, Robert S., Hofmann, Stephan, Keyser, Ulrich F.
Format: Article
Language:English
Subjects:
ABUNDANCE
Applied physics
AQUEOUS SOLUTIONS
Atomic layer epitaxy
CHEMICAL VAPOR DEPOSITION
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
COMPARATIVE EVALUATIONS
Concentration gradient
Current voltage characteristics
CURRENTS
Defects
ELECTRIC POTENTIAL
GRAPHENE
HYDROCHLORIC ACID
HYDROGEN IONS 1 PLUS
MEMBRANES
Organic chemistry
PROTONS
Selectivity
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Summary: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.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4936335