Ab initio molecular dynamics simulation of proton hopping in a model polymer membrane

Ram Devanathan, Nagesh Idupulapati, Marcel D. Baer, Christopher J. Mundy, Michel Dupuis

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)

Abstract

We report the results of ab initio molecular dynamics simulations of a model Nafion polymer membrane initially equilibrated using classical molecular dynamics simulations. We studied three hydration levels (λ) of 3, 9, and 15 H2O/SO3- corresponding to dry, hydrated, and saturated fuel cell membrane, respectively. The barrier for proton transfer from the SO3--H3O+ contact ion pair to a solvent-separated ion pair decreased from 2.3 kcal/mol for λ = 3 to 0.8 kcal/mol for λ = 15. The barrier for proton transfer between two water molecules was in the range from 0.7 to 0.8 kcal/mol for the λ values studied. The number of proton shuttling events between a pair of water molecules is an order of magnitude more than the number of proton hops across three distinct water molecules. The proton diffusion coefficient at λ = 15 is about 0.9 × 10-5 cm2/s, which is in good agreement with experiment and our previous quantum hopping molecular dynamics simulations.

Original languageEnglish
Pages (from-to)16522-16529
Number of pages8
JournalJournal of Physical Chemistry B
Volume117
Issue number51
DOIs
Publication statusPublished - Dec 27 2013

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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