Ion-Specific Nanoconfinement Effect in Multilayered Graphene Membranes: A Combined Nuclear Magnetic Resonance and Computational Study.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 37315026.
- Also identified by DOI 10.1021/acs.nanolett.3c00877.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Ion adsorption within nanopores is involved in numerous applications. However, a comprehensive understanding of the fundamental relationship between in-pore ion concentration and pore size, particularly in the sub-2 nm range, is scarce. This study investigates the ion-species-dependent concentration in multilayered graphene membranes (MGMs) with tunable nanoslit sizes (0.5-1.6 nm) using nuclear magnetic resonance and computational simulations. For Na<sup>+</sup>-based electrolytes in MGMs, the concentration of anions in graphene nanoslits increases in correlation with their chaotropic properties. As the nanoslit size decreases, the concentration of chaotropic ion (BF<sub>4</sub><sup>-</sup>) increases, whereas the concentration of kosmotropic ions (Cit<sup>3-</sup>, PO<sub>4</sub><sup>3-</sup>) and other ions (Ac<sup>-</sup>, F<sup>-</sup>) decreases or changes slightly. Notably, anions remain more concentrated than counter Na<sup>+</sup> ions, leading to electroneutrality breakdown and unipolar anion packing in MGMs. A continuum modeling approach, integrating molecular dynamic simulation with the Poisson-Boltzmann model, elucidates these observations by considering water-mediated ion-graphene non-electrostatic interactions and charge screening from graphene walls.