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@INPROCEEDINGS{Rodenbcher:1024853,
      author       = {Rodenbücher, Christian and Chen, Yingzhen and Wippermann,
                      Klaus and Korte, Carsten},
      title        = {{N}anoscale {I}nvestigations of the {E}lectric {D}ouble
                      {L}ayer in {P}rotic {I}onic {L}iquids},
      issn         = {2151-2043},
      reportid     = {FZJ-2024-02519},
      year         = {2023},
      abstract     = {A hydrogen-based energy storage system will be the backbone
                      of a future energy grid using renewable energies. Polymer
                      electrolyte membrane fuel cells (PEMFCs) are a key element
                      in this energy system as they convert chemical energy stored
                      as hydrogen into electrical energy on demand. PEMFC systems,
                      especially for automotive application, could be
                      significantly improved by increasing the operation
                      temperature above 100 °C. Protic ionic liquids are
                      promising candidates as non-aqueous protic electrolytes for
                      next-generation high-temperature polymer electrolyte
                      membrane fuel cells. These fuel cells have a target
                      operation temperature of 160 °C and allowing for a more
                      efficient water and heat management compared to conventional
                      Nafion®-based PEMFCs, which operate at temperatures below
                      80 °C [1].In order to ensure a reliable and efficient
                      operation an electrolyte with a high electrochemical
                      performance and stability has to be selected. For this
                      purpose, protic ionic liquids have been proposed and first
                      fuel cell tests have shown promising results [2]. Hence, we
                      aim on understanding the properties of this class of novel
                      electrolytes on an atomistic level, which would allow
                      designing suitable material combinations and predicting
                      their properties for an efficient fuel cell operation. As
                      ionic liquids are molten salts, which are liquid below 100
                      °C, their electrochemical properties differ significantly
                      from those of aqueous solutions. Instead of a classical
                      electric double layer, which can be described by the models
                      provided by Helmholtz, Gouy-Chapman and Stern, the interface
                      structure formed between the electrolyte and a charged
                      electrode is governed by the interplay between coulomb
                      interaction and steric effects between the (large) molecular
                      ions [3]. In order to understand the formation of this
                      double layer on a metallic electrode, we employ atomic force
                      microscopy and infrared spectroscopy in combination with
                      molecular dynamics simulations. Our results show that in the
                      interface region between the prototype protic ionic liquid
                      diethylmethylammonium triflate ([Dema][TfO]) and a Pt
                      electrode, a dense layered structure consisting of
                      alternating anion and cation layers is present, that extends
                      several nanometres into the bulk of the electrolyte [4]. The
                      composition and structure changes with applied potential due
                      to a preferential attraction of anions or cations depending
                      on the electrode charge. When water is added to the ionic
                      liquid, the layered structure becomes distorted and water
                      molecules appear near the electrode. Since the presence of
                      water will also influence the relevant electrochemical
                      processes such as the oxygen reduction reaction (ORR), the
                      analysis of the double layer structure on an atomistic scale
                      is necessary in order to understand the subtle interactions
                      between the molecules in the electrolyte and to propose
                      design routes for novel more efficient ionic liquid-based
                      electrolytes.Wippermann, K.; Suo, Y.; Korte, C. Oxygen
                      Reduction Reaction Kinetics on Pt in Mixtures of
                      Proton-Conducting Ionic Liquids and Water: The Influence of
                      Cation Acidity. J. Phys. Chem. C2021, 125, 4423–4435,
                      doi:10.1021/acs.jpcc.0c11374.Skorikova, G.; Rauber, D.;
                      Aili, D.; Martin, S.; Li, Q.; Henkensmeier, D.; Hempelmann,
                      R. Protic Ionic Liquids Immobilized in Phosphoric Acid-Doped
                      Polybenzimidazole Matrix Enable Polymer Electrolyte Fuel
                      Cell Operation at 200 °C. Journal of Membrane Science2020,
                      608, 118188, doi:10.1016/j.memsci.2020.118188.Rodenbücher,
                      C.; Wippermann, K.; Korte, C. Atomic Force Spectroscopy on
                      Ionic Liquids. Applied Sciences2019, 9, 2207,
                      doi:10.3390/app9112207.Rodenbücher, C.; Chen, Y.;
                      Wippermann, K.; Kowalski, P.M.; Giesen, M.; Mayer, D.;
                      Hausen, F.; Korte, C. The Structure of the Electric Double
                      Layer of the Protic Ionic Liquid [Dema][TfO] Analyzed by
                      Atomic Force Spectroscopy. International Journal of
                      Molecular Sciences2021, 22, 12653,
                      doi:10.3390/ijms222312653.},
      month         = {May},
      date          = {2023-05-28},
      organization  = {243rd ECS Meeting, Boston (USA), 28
                       May 2023 - 2 Jun 2023},
      cin          = {IEK-14},
      ddc          = {540},
      cid          = {I:(DE-Juel1)IEK-14-20191129},
      pnm          = {1231 - Electrochemistry for Hydrogen (POF4-123)},
      pid          = {G:(DE-HGF)POF4-1231},
      typ          = {PUB:(DE-HGF)1},
      doi          = {10.1149/MA2023-02562718mtgabs},
      url          = {https://juser.fz-juelich.de/record/1024853},
}