Understanding the mechanism of nitrogen transport in the perfluorinated sulfonic-acid hydrated membranes via molecular dynamics simulations

Innovative Insight into O2/N2 Permeation Behavior through an Ionomer Film in Cathode Catalyst Layers of Polymer Electrolyte Membrane Fuel Cells

“…It is clearly observed that the diffusion coefficients of both O 2 and N 2 increase monotonically with the hydration level, just as speculated. 18,24 Moreover, it should be noted that the diffusion coefficients of O 2 are all higher than those of N 2 under the current hydration levels due to O 2 molecules possessing a larger motion area. Similar diffusion properties of O 2 and N 2 have also been found in pure water.…”

“…The as-increased water uptake will promote the connectivity of interfacial gas channels, thus helping to improve the long-distance diffusion of gas molecules, as further verified by the diffusion coefficients of O 2 and N 2 molecules in bulk Nafion in Figure b. It is clearly observed that the diffusion coefficients of both O 2 and N 2 increase monotonically with the hydration level, just as speculated. , Moreover, it should be noted that the diffusion coefficients of O 2 are all higher than those of N 2 under the current hydration levels due to O 2 molecules possessing a larger motion area. Similar diffusion properties of O 2 and N 2 have also been found in pure water …”

“…Fan et al illustrated that O 2 molecules permeated through the Pt-ionomer interface mainly by water domains, while in the bulk ionomer regions, they diffuse via small cavities at low hydration level and large interfacial areas at higher hydration level . Moreover, the hydration level also affects the N 2 transport and solubility in the hydrated membranes. , Cui et al indicated that N 2 molecules tend to migrate from polymer regions to interfacial regions as the hydration level increases, with a consequent increase in self-diffusion coefficients . Therefore, it is speculated that the hydration level drastically influences the permeation behavior of gas molecules in the ionomer film, and it is critical to identify the transport mechanism as well as preferred location in the hydrated ionomer film.…”

The Evolution of Hydrogen Bond Network in Nafion via Molecular Dynamics Simulation

“…All simulations were performed using GROMACS package − under the condition of three-dimensional periodic boundary. The simulation conditions were the same as our previous study . The Nosé–Hoover thermostat and the Parrinello–Rahman barostat , were employed to control the temperature and pressure.…”

“…The phase separation behavior − and self-assembly behavior in solvents − of Nafion were mainly studied by coarse-grained simulations. The transport of gases, − protons, and water − in Nafion were studied by all-atom molecular dynamics simulations. The Grotthuss mechanism of proton transport was studied by the means of ab initio calculations − and reactive molecular dynamics (RMD). − The studies on HBN of Nafion system are mainly focused on all-atom scale simulation.…”