On the Chemistry and Diffusion of Hydrogen in the Interstitial Space of Layered Crystals h-BN, MoS2, and Graphite

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Yun An - , Leipzig University (Author)
  • Agnieszka Kuc - , Leipzig University, Helmholtz-Zentrum Dresden-Rossendorf, Jacobs University Bremen (Author)
  • Petko Petkov - , Sofia University St. Kliment Ohridski (Author)
  • Marcelo Lozada-Hidalgo - , University of Manchester (Author)
  • Thomas Heine - , Chair of Theoretical Chemistry, Leipzig University, Helmholtz-Zentrum Dresden-Rossendorf (Author)

Abstract

Recent experiments have demonstrated transport and separation of hydrogen isotopes through the van der Waals gap in hexagonal boron nitride and molybdenum disulfide bulk layered materials. However, the experiments cannot distinguish if the transported particles are protons (H+) or protium (H) atoms. Here, reported are the theoretical studies, which indicate that protium atoms, rather than protons, are transported through the gap. First-principles calculations combined with well-tempered metadynamics simulations at finite temperature reveal that for h-BN and MoS2, the diffusion mechanism of both protons and protium (H) atoms involves a hopping process between adjacent layers. This process is assisted by low-energy phonon shear modes. The extracted diffusion coefficient of protium matches the experiment, while for protons it is several orders of magnitude smaller. This indicates that protium atoms are responsible for the experimental observations. These results allow for a comprehensive interpretation of experimental results on the transport of hydrogen isotopes through van der Waals gaps and can help identify other materials for hydrogen isotope separation applications.

Details

Original languageEnglish
Article number1901722
JournalSmall
Volume15
Issue number43
Publication statusPublished - 1 Oct 2019
Peer-reviewedYes

External IDs

PubMed 31489977

Keywords

Keywords

  • 2D membranes, diffusion, free-energy surface, proton and atomic hydrogen diffusion, well-tempered metadynamics simulations