Aqueous Proton Transfer Across Single Layer Graphene

Abstract

Proton transfer across single layer graphene is associated with large computed energy barriers and is therefore thought to be unfavorable at room temperature unless nanoscale holes or dopants are introduced, or a potential bias is applied. Here, we subject single layer graphene supported on fused silica to cycles of high and low pH and show that protons transfer reversibly from the aqueous phase through the graphene to the other side where they undergo acid-base chemistry with the silica hydroxyl groups. After ruling out diffusion through macroscopic pinholes, the protons are found to transfer through rare, naturally occurring atomic defects. Computer simulations reveal low energy barriers of 0.68 to 0.75 eV for aqueous proton transfer across hydroxyl-terminated atomic defects that participate in a Grotthuss-type relay, while pyrylium-like ether terminations shut down proton exchange. Unfavorable energy barriers to helium and hydrogen transfer indicate the transfer process is selective for aqueous protons.

80 pages, including Supporting Information, 3 Figures, 1 Table, final pre-edited version

References in corpus (10)

• The Raman Fingerprint of Graphene
• Quantifying defects in graphene via Raman spectroscopy at different excitation energies
• Unimpeded permeation of water through helium-leak-tight graphene-based membranes
• Impermeable Atomic Membranes from Graphene Sheets
• Precise and ultrafast molecular sieving through graphene oxide membranes
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• Proton transport through one atom thick crystals
• An accurate measurement of electron beam induced displacement cross sections for single-layer graphene
• Graphene re-knits its holes
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• Perfect proton selectivity in ion transport through two-dimensional crystals
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• Relative Permittivity in the Electrical Double Layer from Nonlinear Optics
• Measuring the Proton Selectivity of Graphene Membranes
• Density Functional Based Simulations of Proton Permeation of Graphene and Hexagonal Boron Nitride
• 2D nanoporous membrane for cation removal from water: effects of ionic valence, membrane hydrophobicity and pore size
• Proton and molecular permeation through the basal plane of monolayer graphene oxide
• Gas Barrier Performance of Graphene/Polymer Nanocomposites
• Quantum Filtering of Hydrogen Isotopes through Graphene
• Stern and Diffuse Layer Interactions During Ionic Strength Cycling
• Observation of Structure Evolution and Reaction Intermediates at the Gate-tunable Suspended Graphene/Electrolyte Interface
• Graphene-Complex-oxide Nanoscale Device Concepts