Proton and Li-Ion Permeation through Graphene with Eight-Atom-Ring Defects

Abstract

Defect-free graphene is impermeable to gases and liquids [1][2][3][4] but highly permeable to thermal protons [5][6][7][8] . Atomic-scale defects such as vacancies, grain boundaries and Stone-Wales defects are predicted [9][10][11] to enhance graphene's proton permeability and may even allow small ions through, whereas larger species such as gas molecules should remain blocked. These expectations have so far remained untested in experiment. Here we show that atomically thin carbon films with a high density of atomic-scale defects continue blocking all molecular transport, but their proton permeability becomes ~1,000 times higher than that of defect-free graphene. Lithium ions can also permeate through such disordered graphene. The enhanced proton and ion permeability is attributed to a high density of 8-carbon-atom rings. The latter pose approximately twice lower energy barriers for incoming protons compared to the 6-atom rings of graphene and a relatively low barrier of ~0.6 eV for Li ions. Our findings suggest that disordered graphene could be of interest as membranes and protective barriers in various Li-ion and hydrogen technologies.Despite being a one-atom-thick material, no more than a few gas atoms per hour can permeate through micrometer-sized defect-free graphene membranes, as proven experimentally 3 . Even the smallest ions are blocked by the crystal 4 . These phenomena arise because the dense electron clouds of graphene's crystal lattice impose energy barriers of several eV to incoming molecular and ionic species [9][10][11] , which forbids their permeation under ambient conditions. In contrast, it has been shown experimentally that protons, nuclei of hydrogen atoms, can transport through defect-free graphene relatively easily, overcoming an energy barrier of only ≲1 eV (refs 3-6 ). In this context, theory predicts

Stone–Wales Defects Cause High Proton Permeability and Isotope Selectivity of Single‐Layer Graphene

“…We have calculated the energy profiles and the resulting transfer flow of H + , D + , and T + through the five‐, six‐, and seven‐membered rings in a coronene flake model structure, and for a corresponding 6MR model of h BN (see Supporting Information). The potential energy profiles of the cluster models are very similar to those obtained for a proton penetrating periodic graphene models calculated by us (for details, see Section “Periodic supercell models” in Supporting Information) and Griffin et al [ 25 ]…”

Catalytic activity of graphene-covered non-noble metals governed by proton penetration in electrochemical hydrogen evolution reaction

“…In addition, the energy barriers for GLs are almost proportional to the number of GLs (2GL: 1.76 ± 0.04 eV) while the energy barriers for NGLs are not simply proportional to the number of NGLs (3NGL: 1.17 ± 0.02 eV, 6 NGL: 1.42 ± 0.02 eV). These results indicate that the nitrogen dopant-induced defects on the graphene lattice accelerate the proton penetration 26 . Moreover, the I-V curves of 6NGL demonstrated a non-linear behaviour at a wide voltage range from −3.5 to +3.0 V ( Supplementary Fig.…”

Inhibition of Lithium Dendrite Formation in Lithium Metal Batteries via Regulated Cation Transport through Ultrathin Sub‐Nanometer Porous Carbon Nanomembranes

“…Previous study on ion permeation through CNMs shows the possibility of the Li ion permeation through the sub‐nanometer ion conducting channels. [ 30 ] In this work, the CNM is transferred onto commercial Celgard 2325 tri‐layer separator using advanced techniques that prevent any damage to the CNM layer. A systematic investigation of the role of CNMs in LMBs has been elucidated through microscopic, spectroscopic, electrochemical, and computational modeling studies.…”