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@INPROCEEDINGS{Rameker:1020572,
      author       = {Rameker, Robert and Pluem, Maik and Jovanovic, Sven and
                      Schmid, Guenter and Eichel, Rüdiger-A. and Granwehr, Josef},
      title        = {{D}egradation studies of a short-side-chained {PFSA}
                      material for industrial water electrolysis by {MAS} and
                      {PFG}-{NMR}},
      school       = {RWTH Aachen},
      reportid     = {FZJ-2024-00267},
      year         = {2023},
      note         = {additional grant names: H2 giga, DERIEL, number: 03 HY122A},
      abstract     = {As the ongoing climate change demands alternative energy
                      sources to fossil fuels, the acidic water electrolysis to
                      produce green hydrogen is growing in importance. A critical
                      cornerstone of an electrolyser for acidic water electrolysis
                      is the proton exchange membrane (PEM), which is intended to
                      provide reliable separation of the anode and cathode
                      compartments while ensuring high proton conductivity. In
                      addition, the PEM serves as a carrier for the electrode
                      material to form a membrane electrode assembly (MEA).To
                      operate acidic water electrolysis economically the PEM must
                      be resistant to degradation in order to maximize its
                      lifetime. On a molecular level the polymer is attacked by
                      radicals formed in various side reactions during
                      electrolysis. The influence of the MEA preparation procedure
                      on PEM degradation has been rarely discussed so far. In
                      addition, the electrodynamic parameters of the acidic water
                      electrolysis itself affect the stability and lifetime of a
                      PEM polymer.1Nuclear magnetic resonance (NMR) spectroscopy
                      has proven to be a powerful method for analysing the
                      structural properties of polymers and ionomers. For this
                      reason, NMR spectroscopy was used to study the changes in
                      PEM structure and properties during MEA preparation and
                      electrolysis operation. Thereby, it was essential to find a
                      suitable reference point that allows a quantitative
                      evaluation of the various influences on PEM degradation. In
                      this work changes in chemical structure of a
                      short-side-chained perfluorinated ionomer were investigated
                      using 19F MAS NMR experiments. The relaxation times of the
                      functional groups before and after PEM degradation were
                      compared to detect changes concerning the mobility and
                      chemical environment of the functional groups. The observed
                      relaxation data suggest that degradation decreases the
                      mobility of the individual groups due to chain fracture and
                      crosslinking, as it has already been demonstrated for
                      long-side-chained PEMs.2 In addition, the signal intensities
                      of the individual functional groups before and after PEM
                      degradation have been tracked to identify sites that are
                      vulnerable to degradation. These data suggest that the side
                      chain is more degraded than the polymer backbone. In
                      addition, PFG-NMR was applied to study the proton
                      conductivity as a function of PEM degradation, where the
                      water uptake ratio plays a major role.3Literature:[1] S. H.
                      Frensch et al., International Journal of Hydrogen Energy
                      2019, 44, 29889-29898[2] L. Ghassemzadeh et al., The Journal
                      of Physical Chemistry C 2010, 114, 34, 14635-14645[3] Ochi
                      et al., Solid State Ionics 2009, 180, 6-8, 580-584},
      month         = {Sep},
      date          = {2023-09-18},
      organization  = {FGMR Annual Discussion Meeting 2023,
                       Konstanz (Germany), 18 Sep 2023 - 21
                       Sep 2023},
      subtyp        = {Panel discussion},
      cin          = {IEK-9},
      cid          = {I:(DE-Juel1)IEK-9-20110218},
      pnm          = {1231 - Electrochemistry for Hydrogen (POF4-123) / HITEC -
                      Helmholtz Interdisciplinary Doctoral Training in Energy and
                      Climate Research (HITEC) (HITEC-20170406)},
      pid          = {G:(DE-HGF)POF4-1231 / G:(DE-Juel1)HITEC-20170406},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/1020572},
}