Perfluorosulfonate acid ionomer

The electrolyte is a perfluorosulfonic acid ionomer, commercially available under the trade name of Nafion . It is in the form of a membrane about 0.17 mm (0.007 in) thick, and the electrodes are bonded directly onto the surface. The elec trodes contain veiy finely divided platinum or platinum alloys supported on carbon powder or fibers. The bipolar plates are made of graphite or metal. 

The evaluation of catalysts typically uses two techniques. The first is evaluation as a thin layer on a bulk electrode (e.g., glassy carbon) in dilute liquid electrolyte (e.g., H2 4) either as a static electrode or an RDE. In the study of oxygen reduction, there has been much discussion as to the most appropriate electrolyte to use. In general, dilute perchloric acid (HCIOJ is preferred because of its noncoordinating nature, it is thus closest to the environment foxmd within a FEM catalyst layer with perfluorosulfonic acid ionomer. A possible alternative is trifluoromethylsulfonic acid (CF3SO3H), which mimics perfluorosulfonic acids closely, but there are relatively few studies with this acid. Rotating... 

Mauritz, K. A., Stefanithis, I. D., Davis, S. V., Scheetz, R. W, Pope, R. K., Wilkes, G. L. and Huang, H. H. 1995. Microstructural evolution of a silicon-oxide phase in a perfluorosulfonic acid ionomer by an in situ sol-gel reaction. Journal of Applied Polymer Science 55 181-190. 

An adequate structure of polymer molecules promotes the advantageous phase separation into hydrophobic and hydrophilic domains upon water uptake. The most notable class of membranes based on this principle are the perfluorosulfonic acid ionomers (PFSI), Nafion [26] and similar membranes [27]. In these membranes, perfluorosulfonate side chains, terminated with hydrophilic —SO3H groups, are attached to a hydrophobic fluorocarbon backbone. The tendency of ionic groups to aggregate into ion clusters due to the amphiphilic nature of the ionomer leads to the formation of basic aqueous units. At sufficient humidity these units first get connected by narrow channels and then may even fuse to provide continuous aqueous pathways [28]. 

Kreuer et al. [25] investigated the membrane properties, including water sorption, transport (proton conductivity, electro-osmotic water drag and water diffusion), microstructure and viscoelasticity of the short-side-chain (SSC) perfluorosulfonic acid ionomers (PFSA, Dow 840 and Dow 1150) with different lEC-values. The data were compared to those for Nafion 117, and the implications for using such ionomers as separator materials in direct methanol and hydrogen fuel cells discussed. Tire major advantages of PFSA membranes were seen to be (i) a high proton conductivity. 

S.C. Savett, J.R. Atkins, C.R. Sides, J.L. Harris, B.H. Thomas, S.E. Creager, W.T. Pennunington and D.D. DesMarteau, A comparison of bis[(perfluoroalkyl)-sulfonyl]-imide ionomers and perfluorosulfonic acid ionomers for applications in PEM fuel-technology, J. Electrochem. Soc., 2002, 149, A1527-A1532. 

Cation-exchange membranes, perfluorosulfonic acid ionomer, 125... 

Pellegrino J, Wang D, Rabago R, Noble RD, Koval CA. Gas transport properties of solution-cast perfluorosulfonic acid ionomer films containing ionic surfactants. J Membr Sci 1993 84 161-169. 

Polymer electrolyte membrane Polymer electrolyte membrane fuel cell Pulse field gradient NMR spectroscopy Perfluorosulfonic acid ionomer... 

Numerous polymers have been studied for their potential apphcation in PEMFCs. Based on their chemical structure, these polymers can be categorized into (a) vinylic polymers, (b) aromatic polymers, and (c) polymer blends and composite/hybrid polymers. Generally, vinylic polymers are synthesized by addition polymerization, while aromatic polymers are synthesized by step-growth polymerization. The most studied vinylic polymers for PEMFC applications are perfluorosulfonic acid ionomers (PFSls), in particular Nation , and styrene sulfonic acid-based polymers. Chemical structures of representative vinyhc PEMs are shown in Scheme 2. 

R.A. Zoppi, I.V. P. Yoshida, S. P. Nunes, Hybrids of perfluorosulfonic acid ionomer and silicon oxide by sol-gel reaction from solution Morphology... 

Subianto S, Cavaliere S, Jones D J and Rozidre J (2013), Effect of side chain length on the electrospinning of perfluorosulfonic acid ionomers . Polymer, 51,118-128. 

J.H. Han, K.W. Lee, G.W. Jeon, C.E. Lee, W.K. Park, E.H. Choi, H nuclear magnetic resonance study of hydrated water dynamics in perfluorosulfonic acid ionomer NAFION, Appl. Phys. Lett. 106 (2015) 023104. 

K.D. Kreuer, M. Schuster, B. Obliers, O. Diat, U. Traub, A. Fuchs, U. Klock, S.J. Paddison, J. Maier, Short-side-chain proton conducting perfluorosulfonic acid ionomers why they perform better in PEM fuel cells, J. Power Sources 178 (2008) 499-509. 

L. Ghassemzadeh, K.D. Kreuer, J. Maier, K. Mueller, Evaluating chemical degradation of proton conducting perfluorosulfonic acid ionomers in a Fenton test by sohd-state F NMR spectroscopy, J. Power Sources 196 (2011) 2490—2497. 

Ogumi Z (2010) Aminated perfluorosulfonic acid ionomers to improve the triple phase boundary region in anion-exchange membrane fuel cells. J Elecliochem Soc 157(11) A1153-A1157. doi 10.1149/ 1.3483105... 

Main fluoromaterial applications for the current energy storage technologies are listed in Table 17.5. Most of the processes using fluoropolymers in energy transformation are related to hydrogen economy and the PFSA (perfluorosulfonic acid) ionomers. 

Since a perfluorosulfonic acid ionomer such as Nafion is normally used to make the catalyst layer, trifluoromethane sulfonic acid (CF3SO3H) is expected to behave more closely to the ionomer than the inorganic acids are. In addition, CF3SO3H and its anion (CF3SO3 ) do not adsorb onto the surface of the Pt catalyst and thus do not affect the reaction kinetics. 

Key words electrolyte, membrane, proton conductor, perfluorosulfonic acid, ionomer, acid-doped membranes, sulfonic acid, phosphonic acid, heterocycle,... 

Zhang YM, Li L, Tang JK, Bauer B, Zhang W et al. (2009) Development of covalently cross-linked and composite perfluorosulfonic acid membranes . ECS Trans. 25 1469. Gao HR, Jones DJ, Roziere J, Zhang YM (2011) Cross-linking of the short-side-chain perfluorosulfonic acid ionomer . Manuscript in preparation. 

Ghassemzadeh, L., Marrony, M., Barrera, R., Kreuer, K. D., Maier, and Muller, K. 2009. Chemical degradation of proton conducting perfluorosulfonic acid ionomer membranes studied by solid-state nuclear magnetic resonance spectroscopy. Journal of Power Sources 186 334-338. 

Kreuer, K. D., Schuster, M., Obhers, B., Diat, O., Traub, U., Fuchs, A., Klock, U., Paddison, S. J., and Maier, J. 2008. Short-side-chain proton conducting perfluorosulfonic acid ionomers Why they perform better in PEM fuel cells. 178(2), 499-509. 

Sulfonated polystyrene grafted onto polytetrafluoroethylene. Perfluorosulfonic acid ionomer. 

Heat-treated perfluorosulfonic acid ionomer (Nafion N117). Estimated value from the selectivity of CO2 over CH4. f Estimated value from the selectivity of CO2 over CO. 

Stefanithis I.D., Mauritz K.A. Microstructural evolution ofa silicon oxide phase in a perfluorosulfonic acid ionomer by an in situ sol-gel reaction. 3. Thermal analysis studies. Macromolecules 1990 ... 

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