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@INPROCEEDINGS{Jovanovic:1010211,
      author       = {Jovanovic, Sven and Rameker, Robert and Bagherzadeh, Elahe
                      Saboor and Malmberg, Stephan and Eichel, Rüdiger-A. and
                      Granwehr, Josef},
      title        = {{MAS} and {PFG} {NMR} studies of proton exchanges membranes
                      for electrolytic water splitting},
      reportid     = {FZJ-2023-03020},
      year         = {2023},
      abstract     = {Proton exchange membranes (PEMs) are a critical component
                      in acidic water electrolyzers. They serve the purpose of
                      separating cathode and anode compartments and thus
                      preventing a loss in faradaic efficiency, while
                      simultaneously providing a high proton conductivity for
                      charge compensation. In order to minimize the ohmic losses
                      during electrolysis, the electrode material is often coated
                      directly onto the PEM in order to create a
                      membrane-electrode-assembly (MEA) [1].While high ionic
                      conductivity and impermeability for electrolysis products
                      are crucial properties of a PEM, long-term stability and
                      resistance to chemical and structural alteration are a
                      decisive factor for their industrial application. It is
                      assumed that losses in the stability of the polymer occur
                      due to the formation and attack of radicals on the polymer
                      backbone and the side chains. In particular, the polar side
                      chains are responsible for the formation of hydrophilic
                      channels inside the polymer which promote the proton
                      transport of the material. The Fenton reaction, where iron
                      cations react with peroxide formed during electrolysis, is
                      discussed to be a main mechanism of radical formation
                      [2].Nuclear magnetic resonance (NMR) spectroscopy has been
                      established as a powerful tool for the investigation of
                      polymers and especially ionomers. In this study, magic angle
                      spinning (MAS) and pulsed field gradient (PFG) NMR
                      techniques has been applied for the investigation of the
                      Fenton reaction in short-side-chained PEM materials. The
                      PEMs were treated in a Fenton reagent, i.e. an aqueous
                      solution of Fe(ii) and H2O2. In addition, the PEMs were
                      treated in an aqueous iron(ii) solution as a reference
                      experiment. The effect of Fenton degradation on the chemical
                      structure and chain mobility was studied using MAS NMR
                      experiments, and changes in proton transport properties were
                      assessed by PFG NMR. It was shown that radicals
                      preferentially attack the side chains of the PEM polymer,
                      which decreases the overall mobility of the polar groups and
                      thus affects proton mobility.We thankfully acknowledge
                      funding and support by the Bundesministerium für Bildung
                      und Forschung (BMBF). [1] S. Shiva Kumar et al., Materials
                      Science for Energy Technologies, 2. 442-454, 2019.[2] L.
                      Ghassemzadeh et al., Journal of Power Sources, 196,
                      2490-2497, 2011.},
      month         = {May},
      date          = {2023-05-24},
      organization  = {3rd Conference of the GDCh division of
                       Chemistry and Energy, Pfinztal
                       (Germany), 24 May 2023 - 25 May 2023},
      subtyp        = {Panel discussion},
      cin          = {IEK-9},
      cid          = {I:(DE-Juel1)IEK-9-20110218},
      pnm          = {1232 - Power-based Fuels and Chemicals (POF4-123)},
      pid          = {G:(DE-HGF)POF4-1232},
      typ          = {PUB:(DE-HGF)24},
      url          = {https://juser.fz-juelich.de/record/1010211},
}