Regensburg 2019 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 59: 2D Materials III: Nanomembranes, hBN, and Particle Interactions

O 59.6: Vortrag

Mittwoch, 3. April 2019, 16:30–16:45, H16

How Graphene and Hexagonal Boron Nitride Get Electrified in Water? — •Benoit Grosjean, Marie-Laure Bocquet, and Rodolphe Vuilleumier — PASTEUR, Département de chimie, École normale supérieure, PSL University, Sorbonne Université, CNRS, 75005, Paris, France

The recent emergence of nanofluidics has highlighted the exceptional properties of graphene and its boron-nitride counterpart (hBN) as confining materials for water and ion transport. Surprinsingly ionic transport experiments have unveiled a large electrification of the water-BN surfaces, with a contrasting response for its water-carbon homologue. This charging was conjectured to originate in the differential hydroxide adsorption on the 2D materials, but the challenge of simulating this elusive anion has precluded a proper explanation up to now. We report free energy calculations based on ab initio molecular dynamics simulations of a hydroxide in water near graphene and hBN layers. Our results(1) disclose that both surfaces electrify by hydroxide adsorption via different mechanisms. OH- shows strong chemisorption on hBN, but only weak physisorption on graphene. Interestingly OH- is shown to keep a fast lateral interfacial mobility while physisorbed. Taking into account the resulting large ionic surface mobility, an analytical transport model allows to reproduce quantitatively the experimental data. Our results offer new foundations for the chemical reactivity of carbon and BN materials in water and suggest new perspectives for advanced membrane technologies for water purification and energy harvesting.

(1) B. Grosjean, M.-L. Bocquet and R. Vuilleumier, Submitted, 2018