Tunable Anion-Selective Transport through Monolayer Graphene and Hexagonal Boron Nitride

Çağlar, Mustafa; Silkina, Inese; Brown, Bertram T; Thorneywork, Alice L.; Burton, Oliver J.; Babenko, Vitaliy; Gilbert, Stephen Matthew; Zettl, Alex; Hofmann, Stephan; Keyser, Ulrich F.

doi:10.1021/acsnano.9b08168

Cited by 43 publications

(64 citation statements)

References 53 publications

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“…Although nanopipets ("glass nanopores") have been used previously to probe ion transport through graphene membranes, [8][9][10]15 the SECCM configuration employed herein offers key advantages. In previous reports, 9,15 meniscus-surface contact was detected using isurf feedback with a single channeled probe.…”

Section: Discussionmentioning

confidence: 99%

High-Resolution Ion-Flux Imaging of Proton Transport Through Graphene|Nafion Membranes

Bentley

Kang

Bukola

et al. 2021

Preprint

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In 2014, it was reported that hydrated protons are able to traverse nominally pristine monolayer graphene (and hexagonal boron nitride, h-BN) films under ambient conditions. This “intrinsic proton conductivity” of the one-atom-thick crystals, with proposed through-plane conduction, challenged the notion that graphene is impermeable to atoms, ions and molecules. More recent evidence points to a defect-facilitated transport mechanism, analogous to transport through conventional ion-selective membranes based on graphene and h-BN. To clarify the nature of proton transmission through graphene, local ion-flux imaging is performed herein on graphene|Nafion membranes using a new “electrochemical ion (proton) pump cell” mode of scanning electrochemical cell microscopy (SECCM). Targeting regions of the graphene|Nafion membranes that are free from visible macroscopic defects (e.g., cracks, holes etc.), and assessing hundreds to thousands of different sites across the graphene surfaces in a typical experiment, most of the graphene membrane is impermeable to proton transport, with transmission typically occurring at only ≈20 – 60 localized sites across a ≈0.003 mm2 area of membrane (>5000 measurements, total). When localized proton transport occurs, it can be a highly dynamic process, with new transmission sites “opening” and a small number of sites “closing” under an applied electric field, on the seconds timescale. Applying a simple equivalent circuit model of ion-transport through a cylindrical nanopore, the local transmission sites are estimated to possess dimensions (radii) on the (sub)nanometer-scale, implying that rare atomic defects are responsible for proton conductance through monolayer graphene. Overall, this work reinforces SECCM as a premier tool for the structure−property mapping of microscopically complex (electro)materials, with the new configuration reported herein opening up exciting new possibilities in functional membrane characterization, as well as any other application where reactive ion-flux is a highly localized phenomenon, e.g., for diagnosing failure mechanisms in protective surface coatings.

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Section: Discussionmentioning

confidence: 99%

High-Resolution Ion-Flux Imaging of Proton Transport Through Graphene|Nafion Membranes

Bentley

Kang

Bukola

et al. 2021

Preprint

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“…Producing membranes via chemical vapor deposition is more scalable, but the selectivity of these films is markedly different if atomic‐scale defects are present. Cation and anion‐selective behavior of hBN has also been demonstrated by deliberately introducing lattice defects [ 131 ] or leveraging intrinsic defects [ 132 ] as pores, but these methods are less likely to produce high selectivity due to poor control of pore size.…”

Section: D Materialsmentioning

confidence: 99%

Membrane Materials for Selective Ion Separations at the Water–Energy Nexus

DuChanois¹,

et al. 2021

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Synthetic polymer membranes are enabling components in key technologies at the water–energy nexus, including desalination and energy conversion, because of their high water/salt selectivity or ionic conductivity. However, many applications at the water–energy nexus require ion selectivity, or separation of specific ionic species from other similar species. Here, the ion selectivity of conventional polymeric membrane materials is assessed and recent progress in enhancing selective transport via tailored free volume elements and ion–membrane interactions is described. In view of the limitations of polymeric membranes, three material classes—porous crystalline materials, 2D materials, and discrete biomimetic channels—are highlighted as possible candidates for ion‐selective membranes owing to their molecular‐level control over physical and chemical properties. Lastly, research directions and critical challenges for developing bioinspired membranes with molecular recognition are provided.

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“…In environment, the 2D materials have been used as adsorbents for removing pollutants to treat contaminated water (55)(56)(57). Their atomic thickness and antibacterial activity contribute to superior water permeability and anti-fouling capacity in the development of membranes for desalination (58)(59)(60)(61)(62) and cleaning purposes (63)(64)(65). Sensing has covered both environmental and health sectors, contributing to the detection and monitoring of traces of pollutants (66,67) and blood biomarkers (68)(69)(70)(71).…”

Section: Technological Applications and Innovation Of 2d Materialsmentioning

confidence: 99%

Recent Advances in Immunosafety and Nanoinformatics of Two-Dimensional Materials Applied to Nano-imaging

et al. 2021

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Two-dimensional (2D) materials have emerged as an important class of nanomaterials for technological innovation due to their remarkable physicochemical properties, including sheet-like morphology and minimal thickness, high surface area, tuneable chemical composition, and surface functionalization. These materials are being proposed for new applications in energy, health, and the environment; these are all strategic society sectors toward sustainable development. Specifically, 2D materials for nano-imaging have shown exciting opportunities in in vitro and in vivo models, providing novel molecular imaging techniques such as computed tomography, magnetic resonance imaging, fluorescence and luminescence optical imaging and others. Therefore, given the growing interest in 2D materials, it is mandatory to evaluate their impact on the immune system in a broader sense, because it is responsible for detecting and eliminating foreign agents in living organisms. This mini-review presents an overview on the frontier of research involving 2D materials applications, nano-imaging and their immunosafety aspects. Finally, we highlight the importance of nanoinformatics approaches and computational modeling for a deeper understanding of the links between nanomaterial physicochemical properties and biological responses (immunotoxicity/biocompatibility) towards enabling immunosafety-by-design 2D materials.

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Tunable Anion-Selective Transport through Monolayer Graphene and Hexagonal Boron Nitride

Cited by 43 publications

References 53 publications

High-Resolution Ion-Flux Imaging of Proton Transport Through Graphene|Nafion Membranes

High-Resolution Ion-Flux Imaging of Proton Transport Through Graphene|Nafion Membranes

Membrane Materials for Selective Ion Separations at the Water–Energy Nexus

Recent Advances in Immunosafety and Nanoinformatics of Two-Dimensional Materials Applied to Nano-imaging

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