Diffusion in Nafion

With the exception of Elder et. al., who used EXAFS to look at redox properties of copper complexes diffused in Nafion film modified electrodes (21), no in-situ studies have been reported on modified electrodes using EXAFS. 

Ochi S, Kamishima O, MizusaM J, Kawamura J (2009) Investigation of proton diffusion in Nafion 117 membrane by electrical conductivity and NMR. Solid State Ion 180 580-584... 

CT by reduction of a macrocyclic complex, tetraphenylporphyrin cobalt(lll) ([Co TP ]" ), in a Nafion film was investigated using a PSCAS [38]. The CT mechanism was found to be a physical displacement of [Co TTP]" with kp = 6.2 X 10 s . It was surprising to see CT by such a large and hydrophobic molecule taking place by physical diffusion in Nafion. The reduced species of hydrophobic [Co TPP] had been considered to be unfavorable for diffusion in the hydrophihc ion channel of Nafion. The physical displacement mechanism would suggest that the complexes ([Co TPP]" and [Co TPP]) diffuse in the interfacial region between hydrophobic polyfluorocarbon clusters and the hydrophilic ion channel. 

Yeager HL, Steck A. Cation and water diffusion in Nafion ion-exchange membranes—influence of polymer stmcture. J Electrochem Soc 1981 128(9) 1880-4. 

H. L. Yeager and A. Steck, Cation and water diffusion in nafion ion... 

In the FA model, an elementary conversion unit is a spherical cluster of carbon support immersed in Nafion. The cluster may or may not be covered by a thin electrolyte film. In any case, to reach the catalyst surface an oxygen molecule must dissolve and diffuse in Nafion. Since oxygen... 

Diffusion in Nafion Diffusion into Nation (and other perfl uorosulfonic acid-based membranes) can be modeled according to Pick s law ... 

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