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Title: Effect of bound state of water on hydronium ion mobility in hydrated Nafion using molecular dynamics simulations

We have performed a detailed analysis of the structural properties of the sulfonate groups in terms of isolated and overlapped solvation shells in the nanostructure of hydrated Nafion membrane using classical molecular dynamics simulations. Our simulations have demonstrated the correlation between the two different areas in bound water region, i.e., the first solvation shell, and the vehicular transport of hydronium ions at different water contents. We have employed a model of the Nafion membrane using the improved force field, which is newly modified and validated by comparing the density and water diffusivity with those obtained experimentally. The first solvation shells were classified into the two types, the isolated area and the overlapped area. The mean residence times of solvent molecules explicitly showed the different behaviors in each of those areas in terms of the vehicular transport of protons: the diffusivity of classical hydronium ions in the overlapped area dominates their total diffusion at lower water contents while that in the isolated area dominates for their diffusion at higher water contents. The results provided insights into the importance role of those areas in the solvation shells for the diffusivity of vehicular transport of hydronium ions in hydrated Nafion membrane.
Authors:
 [1] ;  [2]
  1. Graduate School of Engineering, Tohoku University, Sendai, Miyagi 980-8577 (Japan)
  2. Institute of Fluid Science, Tohoku University, Sendai, Miyagi 980-8577 (Japan)
Publication Date:
OSTI Identifier:
22308388
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 10; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BOUND STATE; DIFFUSION; MEMBRANES; MOLECULAR DYNAMICS METHOD; MOLECULES; NANOSTRUCTURES; OXONIUM IONS; PROTONS; SIMULATION; SOLVATION; SOLVENTS; WATER