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@INPROCEEDINGS{Jovanovic:1047385,
      author       = {Jovanovic, Sven and Rameker, Robert and Poc, Jean-Pierre
                      and Jodat, Eva and Karl, André and Eichel, Rüdiger-A. and
                      Granwehr, Josef},
      title        = {{A} novel perspective on accelerated degradation studies of
                      proton exchange membranes},
      publisher    = {Zenodo},
      reportid     = {FZJ-2025-04271},
      pages        = {9},
      year         = {2025},
      abstract     = {Accelerated degradation studies are widely applied in
                      research on proton exchange membranes (PEMs) for the
                      investigation of the origins and mechanisms of performance
                      loss for electrolysis or fuel cell applications. In a
                      nutshell, it is reported in literature that degradation in
                      PEMs commonly occurs following Fenton-like reactions, where
                      in situ formed H2O2 reacts with transition metal cations to
                      produce radicals. These radicals then alter the ionomer on a
                      chemical level by attacking particularly its polar side
                      chains, causing a loss of functional moieties for proton
                      transport [1]. Fast degradation studies mimic and promote
                      these conditions by subjecting PEMs to high concentrations
                      of H2O2 and Fe2+ cations at elevated temperatures. However,
                      these studies often exhibit discrepancies when compared to
                      degradation occurring during long-term operation [2].The
                      presented work attempts to elucidate these discrepancies by
                      i) addressing inconsistencies in accelerated degradation and
                      testing procedures, ii) studying the dependence of
                      degradation on PEM chemistry and structure and iii)
                      utilizing both NMR spectroscopy and SEM microscopy among
                      other techniques for a comprehensive picture. Hereby,
                      solid-state magic angle spinning (MAS) NMR spectroscopy
                      provides information on both chemical and local structural
                      transformations of the PEM, while SEM offers concrete
                      insights into structural changes on a microscopic scale. The
                      Fenton-like accelerated degradation experiments were
                      optimized for homogeneity and effectiveness by introducing
                      the catalytic iron centers into the PEMs. Additionally,
                      interferences in the analytical techniques were minimized by
                      careful removal of excess reactants after accelerated
                      degradation. The combined analytical techniques reveal that
                      chemical degradation in PEMs is significantly less
                      pronounced than suggested in literature, although
                      differences were observed depending on the type of PEM
                      material. Moreover, organic radicals that form during
                      Fenton-like reactions could not be detected by EPR
                      spectroscopy. However, all samples experienced significant
                      changes in the local structure, as indicated by NMR
                      relaxometry, and microscopic structure, as illustrated by
                      SEM techniques. Thus, instead of chemical degradation, the
                      PEM may be affected on a structural level by mechanical
                      stress due to microscopic gas pockets and macroscopic
                      bubbles forming inside the gas impermeable material.[1] L.
                      Ghassemzadeh et al., J. Am. Chem. Soc. 135, 8181–8184
                      (2013).[2] J. Mališ et al., Int. J. Hydrogen Energy 41,
                      2177–2188 (2016).},
      month         = {Jul},
      date          = {2025-07-01},
      organization  = {European Electrolyser $\&$ Fuel Cell
                       Forum (EFCF), Lucerne (Switzerland), 1
                       Jul 2025 - 4 Jul 2025},
      keywords     = {EFCF2025 (Other) / H2 (Other) / LowTemp. Fuel Cells $\&$
                      Electrolysers (Other) / PEMs (Other) / degradation (Other) /
                      Fenton (Other) / analytics (Other)},
      cin          = {IET-1},
      cid          = {I:(DE-Juel1)IET-1-20110218},
      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)8},
      doi          = {10.5281/zenodo.17244134},
      url          = {https://juser.fz-juelich.de/record/1047385},
}