Abstract
Chemical degradation of the side-chain of perfluorosulfonic acid (PFSA) membranes by hydroxyl radicals (•OH) is examined with electronic structure calculations. The energetics associated with homolytic bond cleavage and for the sequence of reactions involved in the degradation was determined. Results show that the degradation of side-chain begins with the cleavage of the C–S bond. The sequence of reactions of the side-chain with dOH indicates scission of the backbone yielding reactive end-groups. The kinetics of the C–S bond cleavage was studied via: (i) reaction of anionic fragment with a •OH; and (ii) decomposition of fragment radical. The activation energy for the second pathway was calculated to be;11 kcal/mol lower requiring a change in symmetry of the molecular geometry of the sulfonate group from trigonal pyramidal to trigonal planar. This suggests that although the C–S bond may be the weakest in the side chain of a PFSA ionomer, its cleavage is kinetically hindered.
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R. Borup, J. Meyers, B. Pivovar, Y.S. Kim, R. Mukundan, N. Garland, D. Myers, M. Wilson, F. Garzon, D. Wood, P. Zelenay, K. More, K. Stroh, T. Zawodzinski, J. Boncella, J.E. McGrath, M. Inaba, K. Miyatake, M. Hori, K. Ota, Z. Ogumi, S. Miyata, A. Nishikata, Z. Siroma, Y. Uchimoto, K. Yasuda, K.I. Kimijima, and N. Iwashita: Scientific aspects of polymer electrolyte fuel cell durability and degradation. Chem. Rev. 107(10), 3904 (2007).
M. Granovskii, I. Dincer, and M.A. Rosen: Life cycle assessment of hydrogen fuel cell and gasoline vehicles. Int. J. Hydrogen Energy 31(3), 337 (2006).
F.N. Buchi, M. Inaba, and T.J. Schmidt: Polymer Electolyte Fuel Cell Durability (Springer, New York, NY, 2009).
J. Wu, X.Z. Yuan, J.J. Martin, H. Wang, J. Zhang, J. Shen, S. Wu, and W. Merida: A review of PEM fuel cell durability: Degradation mechanisms and mitigation strategies. J. Power Sources 184(1), 104 (2008).
A. Collier, H. Wang, X. Zi Yuan, J. Zhang, and D.P. Wilkinson: Degradation of polymer electrolyte membranes. Int. J. Hydrogen Energy 31(13), 1838 (2006).
V.A. Sethuraman, J.W. Weidner, A.T. Haug, and L.V. Protsailo: Durability of perfluorosulfonic acid and hydrocarbon membranes: Effect of humidity and temperature. J. Electrochem. Soc. 155(2), B119 (2008).
M. Inaba, T. Kinumoto, M. Kiriake, R. Umebayashi, A. Tasaka, and Z. Ogumi: Gas crossover and membrane degradation in polymer electrolyte fuel cells. Electrochim. Acta 51(26), 5746 (2006).
S.D. Knights, K.M. Colbow, J. St-Pierre, and D.P. Wilkinson: Aging mechanisms and lifetime of PEFC and DMFC. J. Power Sources 127(1–2), 127 (2004).
Y.A. Yuji Shibahara, Y. Izumi, S. Nishijima, Y. Honda, N. Kimura, S. Tagawa, and G. Isoyama: Analysis of thermal degradation process of Nafion-117 with age-momentum correlation method. J. Polym. Sci., Part B: Polym. Phys. 46(1), 1 (2008).
E. Endoh, S. Terazono, H. Widjaja, and Y. Takimoto: Degradation study of MEA for PEMFCs under low humidity conditions. Electrochem. Solid-State Lett. 7(7), A209 (2004).
C. Chen, G. Levitin, D.W. Hess, and T.F. Fuller: XPS investigation of Nafion® membrane degradation. J. Power Sources 169(2), 288 (2007).
A. Bosnjakovic, M.K. Kadirov, and S. Schlick: Using ESR spectroscopy to study radical intermediates in proton-exchange membranes exposed to oxygen radicals. Res. Chem. Intermed. 33, 677 (2007).
A. Bosnjakovic and S. Schlick: Nafion perfluorinated membranes treated in fenton media: Radical species detected by ESR spectroscopy. J. Phys. Chem. B 108(14), 4332 (2004).
M. Danilczuk, A. Bosnjakovic, M.K. Kadirov, and S. Schlick: Direct ESR and spin trapping methods for the detection and identification of radical fragments in Nafion membranes and model compounds exposed to oxygen radicals. J. Power Sources 172(1), 78 (2007).
T. Kinumoto, M. Inaba, Y. Nakayama, K. Ogata, R. Umebayashi, A. Tasaka, Y. Iriyama, T. Abe, and Z. Ogumi: Durability of perfluorinated ionomer membrane against hydrogen peroxide. J. Power Sources 158(2), 1222 (2006).
A. Pozio, R.F. Silva, M. De Francesco, and L. Giorgi: Nafion degradation in PEFCs from end plate iron contamination. Electrochim. Acta 48(11), 1543 (2003).
T. Okada, Y. Ayato, H. Satou, M. Yuasa, and I. Sekine: The effect of impurity cations on the oxygen reduction kinetics at platinum electrodes covered with perfluorinated ionomer J. Phys. Chem. B 105(29), 6980 (2001).
R. Bauer, G. Waldner, H. Fallmann, S. Hager, M. Klare, T. Krutzler, S. Malato, and P. Maletzky: The photo-Fenton reaction and the TiO2/UV process for waste water treatment - novel developments. Catal. Today 53(1), 131 (1999).
X. Cheng, J.L. Zhang, Y.H. Tang, C.J. Song, J. Shen, D.T. Song, and J.J. Zhang: Hydrogen crossover in high-temperature PEM fuel cells. J. Power Sources 167(1), 25 (2007).
V.O. Mittal, H.R. Kunz, and J.M. Fenton: Membrane degradation mechanisms in PEMFCs. J. Electrochem. Soc. 154(7), B652 (2007).
M. Aoki, H. Uchida, and M. Watanabe: Decomposition mechanism of perfluorosulfonic acid electrolyte in polymer electrolyte fuel cells. Electrochem. Commun. 8(9), 1509 (2006).
J.R. Yu, T. Matsuura, Y. Yoshikawa, M.N. Islam, and M. Hori: In situ analysis of performance degradation of a PEMFC under nonsaturated humidification. Electrochem. Solid-State Lett. 8(3), A156 (2005).
V.O. Mittal, H.R. Kunz, and J.M. Fenton: Effect of catalyst properties on membrane degradation rate and the underlying degradation mechanism in PEMFCs. J. Electrochem. Soc. 153(9), A1755 (2006).
M. Aoki, H. Uchida, and M. Watanabe: Novel evaluation method for degradation rate of polymer electrolytes in fuel cells. Electrochem. Commun. 7(12), 1434 (2005).
A.B. LaConti, M. Hamdan, and R.C. McDonald: Handbook of Fuel Cells: Fundamentals, Technology and Applications (John Wiley & Sons, New York, 2003).
N.E. Cipollini: Chemical aspects of membrane degradation. ECS Trans. 11(1), 1071 (2007).
K. Teranishi, K. Kawata, S. Tsushima, and S. Hirai: Degradation mechanism of PEMFC under open circuit operation. Electrochem. Solid-State Lett. 9(10), A475 (2006).
W. Liu and D. Zuckerbrod: In situ detection of hydrogen peroxide in PEM fuel cells. J. Electrochem. Soc. 152(6), A1165 (2005).
W.E. Delaney and W. Liu: Use of FTIR to analyze ex situ and in situ degradation of perfluorinated fuel cell ionomers. ECS Trans. 11(1), 1093 (2007).
J.L. Qiao, M. Saito, K. Hayamizu, and T. Okada: Degradation of perfluorinated ionomer membranes for PEM fuel cells during processing with H2O2. J. Electrochem. Soc. 153(6), A967 (2006).
S. Mitov, A. Panchenko, and E. Roduner: Comparative DFT study of nonfluorinated and perfluorinated alkyl and alkyl-peroxy radicals. Chem. Phys. Lett. 402(4–6), 485 (2005).
D.E. Curtin, R.D. Lousenberg, T.J. Henry, P.C. Tangeman, and M.E. Tisack: Advanced materials for improved PEMFC performance and life. J. Power Sources 131, 41 (2004).
S. Hommura, K. Kawahara, and T. Shimodaira: Chemical degradation of perfluorinated sulfonic acid membranes. Polym. Prep. Jpn. 54, 4517–4518 (2005).
S.J. Hamrock and M.A. Yandrasits: Proton exchange membranes for fuel cell applications. Polym. Rev. 46(3), 219 (2006).
L. Ghassemadeh, M. Marrony, R. Barrera, K.D. Kreuer, J. Maier, and K. Muller: Chemical degradation of proton-conducting perflurosulfonic acid ionomer membranes studied by solid-state nuclear magnetic resonance spectroscopy. J. Power Sources 186(2), 334 (2009).
X. Fang, P.K. Shen, S. Song, V. Stergiopoulos, and P. Tsiakaras: Degradation of perfluorinated sulfonic acid films: An in situ infrared spectroelectrochemical study. Polym. Degrad. Stab. 94(10), 1707 (2009).
L. Ghassemzadeh, K.D. Kreuer, J. Maier, and K. Mueller: Evaluating chemical degradation of proton-conducting perfluorosulfonic acid ionomers in a Fenton test by solid-state 19F NMR spectroscopy. J. Power Sources 196(5), 2490 (2011).
T. Tokumasu, I. Ogawa, M. Koyama, T. Ishimoto, and A. Miyamoto: A DFT study of bond dissociation trends of perfluorosulfonic acid membrane. J. Electrochem. Soc. 158(2), B175 (2010).
L. Ghassemzadeh, K-D. Kreuer, J. Maier, and K. Muller: Chemical degradation of Nafion membranes under mimic fuel cell conditions as investigated by solid-state NMR spectroscopy. J. Phys. Chem. C 114(34), 14635 (2010).
M.K. Kadirov, A. Bosnjakovic, and S. Schlick: Membrane-derived fluorinated radicals detected by electron spin resonance in UV-irradiated Nafion and Dow ionomers: Effect of counterions and H2O2. J. Phys. Chem. B 109(16), 7664 (2005).
A.H. Carlsson, L. Jorissen, and W. Tillmetz: PFSA Membrane Degradation Mechanism: Fuel Cell Degradationversus. Ex-Situ Methods (Zentrum für Sonnenenergie und Wasserstoff-Forschung, Ulm, Germany, 2009).
F.D. Coms: The chemistry of fuel cell membrane chemical degradation. ECS Trans. 16(2), 235 (2008).
M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman, J.A. Montgomery, T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox, H.P. Hratchian, J.B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M. Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, and J.A. Pople: Gaussian 03 (Gaussian Inc., Wallingford, CT, 2004).
A.D. Becke: Density-functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 98(7), 5648 (1993).
C. Lee, W. Yang, and R.G. Parr: Development of the Colle Salvetti correlation-energy formula into a functional of the electron density. Phys. Rev. B: Condens. Matter 37(2), 785 (1988).
S.H. Vosko, L. Wilk, and M. Nusair: Accurate spin-dependent electron liquid correlation energies for local spin density calculations: A critical analysis. Can. J. Phys. 58(8), 1200 (1980).
P.J. Stephens, F.J. Devlin, C.F. Chabalowski, and M.J. Frisch: Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields. J. Phys. Chem. 98(45), 11623 (1994).
C.Y. Peng and H.B. Schlegel: Combining synchronous transit and quasi-Newton methods to find transition states. Isr. J. Chem. 33(4), 449 (1993).
C. Gonzalez and H.B. Schlegel: An improved algorithm for reaction-path following. J. Chem. Phys. 90, 2154 (1989).
C. Gonzalez and H.B. Schlegel: Reaction-path following in mass-weighted internal coordinates. J. Phys. Chem. 94(14), 5523 (1990).
C. Wang and S.J. Paddison: Proton transfer in functionalized phosphonic acid molecules. Phys. Chem. Chem. Phys. 12(4), 970 (2010).
M. Eikerling, S.J. Paddison, and T.A. Zawodzinski: Molecular orbital calculations of proton dissociation and hydration of various acidic moieties for fuel cell polymers. J. New Mater. Electrochem. Syst. 5(1), 15 (2002).
S.J. Paddison: Proton conduction mechanisms at low degrees of hydration in sulfonic acid-based polymer electrolyte membranes. Annu. Rev. Mater. Res. 33, 289 (2003).
S.J. Paddison and J.A. Elliott: Molecular modeling of the short-side-chain perfluorosulfonic acid membrane. J. Phys. Chem. A 109(33), 7583 (2005).
J.A. Elliott and S.J. Paddison: Modeling of morphology and proton transport in PFSA membranes. Phys. Chem. Chem. Phys. 9(21), 2602 (2007).
J.K. Clark, S.J. Paddison, M. Eikerling, M. Dupuis, and T.A. Zawodzinski: A comparative ab initio study of the primary hydration and proton dissociation of various imide- and sulfonic acid ionomers. J. Phys. Chem. A 116(7), 1801 (2012).
M. Laporta, M. Pegoraro, and L. Zanderighi: Perfluorosulfonated membrane (Nafion): FTIR study of the state of water with increasing humidity. Phys. Chem. Chem. Phys. 1(19), 4619 (1999).
S.J. Paddison: The modeling of molecular structure and ion transport in sulfonic acid-based ionomer membranes. J. New Mater. Electrochem. Syst. 4(4), 197 (2001).
K.D. Kreuer, S.J. Paddison, E. Spohr, and M. Schuster: Transport in proton conductors for fuel-cell applications: Simulations, elementary reactions, and phenomenology. Chem. Rev. 104(10), 4637 (2004).
D.A. Schiraldi: Perfluorinated polymer electrolyte membrane durability. J. Macromol. Sci., Polym. Rev. 46(3), 315 (2006).
C. Zhou, M.A. Guerra, Z-M. Qiu, T.A. Zawodzinski, and D.A. Schiraldi: Chemical durability studies of perfluorinated sulfonic acid polymers and model compounds under mimic fuel cell conditions. Macromolecules 40(24), 8695 (2007).
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This work was supported by the U.S. Department of Energy under the Energy Efficiency and Renewable Energy (EERE) program and through the Sustainable Energy Education and Research Center (SEERC) at the University of Tennessee.
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Kumar, M., Paddison, S.J. Side-chain degradation of perfluorosulfonic acid membranes: An ab initio study. Journal of Materials Research 27, 1982–1991 (2012). https://doi.org/10.1557/jmr.2012.191
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DOI: https://doi.org/10.1557/jmr.2012.191