Nafion

About: Nafion is a research topic. Over the lifetime, 9110 publications have been published within this topic receiving 320865 citations.

Cerium(III) as a Stabilizer of Perfluorinated Membranes Used in Fuel Cells: In Situ Detection of Early Events in the ESR Resonator

Abstract: We present experiments in an in situ fuel cell (FC) inserted in the resonator of the ESR spectrometer that allowed separate monitoring of radical formation at anode and cathode sides. The in situ FC was operated at 300 K under closed and open circuit voltage conditions, CCV and OCV, respectively, with a membrane-electrode assembly (MEA) based on Nafion 117 10% neutralized by Ce(III) and Pt as catalyst, notation MEA/Ce. The presence of the unstable intermediates was determined by addition of 5,5-dimethylpyrroline-N-oxide (DMPO) as a spin trap, simulation of the spectra from the DMPO adducts, and analysis of the corresponding magnetic parameters and relative intensities. The main objective of these experiments was to identify early events in the mitigation mechanism of Ce(III) on Nafion degradation. The present results were therefore compared to an in situ FC based on Nafion 117 in the acid form, notation MEA/H (Danilczuk et al. J. Phys. Chem. B 2009, 113, 8031−8042) that served as baseline. The differences...

Sulfonated Polysulfone/POSS Nanofiber Composite Membranes for PEM Fuel Cells

Abstract: In the present study, an implementation of the polymer/particle composite strategy is demonstrated, where fuel cell membranes are fabricated by electrospinning nanofibers composed of a proton conducting polymer with proton conducting, water-retaining inorganic nanoparticles. Specifically, a nanofiber mat was electrospun from sulfonated polyarylene ether sulfonesPAES to which sulfonated polyhedral oligomeric silsesquioxane sPOSS nanoparticles were added to improve water retention and proton conductivity. The interfiber voids were filled with an acid- and temperature-resistant hydrophobic photocurable polyurethane. This uncharged polymer surrounds each nanofiber, restricts fiber swelling in water, and provides mechanical strength to the membrane, thus permitting a higher loading of inorganic particles and the use of fibers with a fixedcharge concentration much greater than that which is practical in a homogeneous ion-exchange membrane. The resulting phaseseparated nanofiber/matrix-polymer morphology is similar to the desired/ideal bicontinuous structure in a block copolymer system, but there is more flexibility in our fabrication approach. Thus, the ionomer, fiber diameter, fiber volume fraction, and inert polymer can be selected independently. Additionally, the present approach might represent an effective way to fabricate a fluorocarbon-free “green” PEM with good mechanical properties and a conductivity exceeding that of Nafion at RHs less than 100%. Experimental

Potential Bifunctional Filler (CeO2–ACNTs) for Nafion Matrix toward Extended Electrochemical Power Density and Durability in Proton-Exchange Membrane Fuel Cells Operating at Reduced Relative Humidity

Abstract: Cerium oxide–anchored amine-functionalized carbon nanotubes (CeO2–ACNTs) are applied as radical scavengers as well as solid proton conductors to realize hybrids with Nafion (Nafion/CeO2–ACNTs) for ...

Influence of morphology on the transport properties of perfluorosulfonate ionomers/polypyrrole composite membrane

Abstract: Nanosized polypyrrole particles were mainly incorporated into the ionic clusters rather than the nonpolar backbone of Nafion in chemical in-situ polymerization by means of ion−dipole interaction between the sulfonate groups of Nafion and secondary amonium groups of polypyrrole. The incorporation of polypyrrole particles into the clusters, where was the transport pathway, could change the morphology of Nafion matrix, as observed by DSC, SAXS, and WAXD. In particular, the crystallite region of backbones as well as the cluster region of side chains was influenced indirectly by the existence of polypyrrole particles in the ionic clusters. Additionally, the temperature of the cluster transition shifted to a higher value due to the restricted mobility of the clusters, whereas the melting temperature of the nonpolar backbone crystallite shifted to a lower value due to the disruptive effect of swelled cluster. The methanol crossover was reduced more than the proton conductivity because of the existence of polypyr...