| Proton hopping in phosphoric acid solvated nafion membrane: a molecular simulation study. | |
| | |
MedLine Citation:
|
PMID: 17518491 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
|
Molecular simulation studies of the microstructure and of the proton transport properties of phosphoric acid solvated Nafion membrane are carried out. The ab initio calculations show that the phosphoric acid is a good solvent to promote the proton ionization of the sulfonic acid group, and only two phosphoric acid molecules are necessary for the dissociation of one sulfonic acid group. A mechanism of proton hopping between phosphoric acid and protonated phosphoric acid cation in the hydrophilic subphase is also elucidated by ab initio calculations. The molecular dynamics simulations, conducted at a phosphoric acid concentration of 25.4% (wt) which is slightly lower than that of phosphoric acid swollen Nafion, show that the phosphoric acid exists in subphases and that it cannot develop into a continuous subphase. Thus, proton-hopping pathways are interrupted, and the conductivity is expected to be lower than that for pure phosphoric acid. The molecular dynamics simulations, conducted at a phosphoric acid concentration of 45.1% (wt) which corresponds to an unstable state, show that the hydrophobic poly(tetrafluoroethylene) backbones trend to gather together forming hydrophobic clusters and that the phosphoric acid forms a continuous subphase with the sulfonic acid groups located at the hydrophobic/hydrophilic interface. Thus, proton-hopping pathways can develop uninterruptedly like the pure phosphoric acid, and high conductivity is expected. The molecular dynamics study also shows that the hydrogen-bonding characteristics of phosphoric acid and sulfonate anion are similar regardless of the factor that the former can move freely while the latter is attached to Nafion backbone. |
| | |
Authors:
|
Liuming Yan; Suhua Zhu; Xiaobo Ji; Wencong Lu |
Publication Detail:
|
Type: Journal Article Date: 2007-05-23 |
Journal Detail:
|
Title: The journal of physical chemistry. B Volume: 111 ISSN: 1520-6106 ISO Abbreviation: J Phys Chem B Publication Date: 2007 Jun |
Date Detail:
|
Created Date: 2007-06-07 Completed Date: 2007-07-19 Revised Date: - |
Medline Journal Info:
|
Nlm Unique ID: 101157530 Medline TA: J Phys Chem B Country: United States |
Other Details:
|
Languages: eng Pagination: 6357-63 Citation Subset: - |
Affiliation:
|
Department of Chemistry, College of Sciences, Shanghai University, 99 Shangda Road, Shanghai 200444, China. liuming.yan@shu.edu.cn |
Export Citation:
|
APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
|
|
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
Previous Document: Quantitative characterization of ion pairing and cluster formation in strong 1:1 electrolytes.
Next Document: Effect of water and organic solvents on the ionic dissociation of ionic liquids.