Indexed by:Journal Article

Date of Publication:2018-02-01

Journal:JOURNAL OF PHYSICAL CHEMISTRY C

Included Journals:EI、SCIE

Volume:122

Issue:4

Page Number:1982-1989

ISSN:1932-7447

Abstract:The performance of the proton exchange membrane depends on several factors including membrane backbone and side chain, channel size and connectivity, temperature, pressure, electric field, hydration level, etc. However, it is impossible to separately investigate the independent effect of each factor on proton transfer in the membrane. The synergistic relationship between the proton conductive channel environment and the hydrated proton structure plays a decisive role in understanding the mechanism of proton transfer through the proton exchange membrane. In this paper, classical molecular dynamics simulation is adopted to investigate the independent effects of the sulfonate group and fluorine on the confined hydrogen bond network in the proton conductive channel, which is modeled using single-walled carbon nanotubes decorated with sulfonate groups and fluorine atoms. The free energy profile and hydrogen bond arrangement suggest that the aggregated sulfonate groups help trap hydrated protons, and fluorination facilitates the proton dissociation in the proton conductive channel. This is further verified by coordination number of the sulfonate group and hydronium dissociation. Fluorination also maintains the continuous proton transfer by stabilizing the confined hydrogen bond connectivity. These findings provide the understanding of the synergistic effects of the sulfonate group and fluorine on proton transfer along the proton conductive channel of Nafion.