<?xml version="1.0" encoding="utf-8"?>
<export-example>
  <doc>
    <id>12471</id>
    <completedYear/>
    <publishedYear>2014</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>3750</pageFirst>
    <pageLast>3756</pageLast>
    <pageNumber/>
    <edition/>
    <issue>5</issue>
    <volume>2014</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2014-10-28</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">Analyzing Structural Changes of Fe-N-C Cathode Catalysts in PEM Fuel Cell by Mößbauer Spectroscopy of Complete Membrane-Electrode-Assemblies</title>
    <abstract language="eng">The applicability of analyzing by Mößbauer spectroscopy the structural changes of Fe–N–C catalysts that have been tested at the cathode of membrane electrode assemblies in proton exchange membrane (PEM) fuel cells is demonstrated. The Mößbauer characterization of powders of the same catalysts was recently described in our previous publication. A possible change of the iron species upon testing in fuel cell was investigated here by Mößbauer spectroscopy, energy-dispersive X-ray cross-sectional imaging, and neutron activation analysis. Our results show that the absorption probability of γ rays by the iron nuclei in Fe–N–C is strongly affected by the presence of Nafion and water content. A detailed investigation of the effect of an oxidizing treatment (1.2 V) of the non-noble cathode in PEM fuel cell indicates that the observed activity decay is mainly attributable to carbon oxidation causing a leaching of active iron sites hosted in the carbon matrix.</abstract>
    <parentTitle language="eng">The Journal of Physical Chemistry Letters</parentTitle>
    <identifier type="doi">10.1021/jz501955g</identifier>
    <identifier type="issn">1948-7185</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <author>
      <firstName>Ulrike Ingrid</firstName>
      <lastName>Kramm</lastName>
    </author>
    <submitter>
      <firstName>Karsten</firstName>
      <lastName>Henkel</lastName>
    </submitter>
    <author>
      <firstName>Michel</firstName>
      <lastName>Lefèvre</lastName>
    </author>
    <author>
      <firstName>Peter</firstName>
      <lastName>Bogdanoff</lastName>
    </author>
    <author>
      <firstName>Dieter</firstName>
      <lastName>Schmeißer</lastName>
    </author>
    <author>
      <firstName>Jean-Pol</firstName>
      <lastName>Dodelet</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>iron-based catalyst</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>iron−nitrogen−carbon catalyst</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>non-noble metal catalyst</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>nonprecious metal catalyst</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>oxygen reduction reaction</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>ORR</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>polymer electrolyte membrane fuel cell</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>PEM-FC</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>degradation</value>
    </subject>
    <collection role="old_institute" number="01005">LS Angewandte Physik / Sensorik</collection>
    <collection role="institutes" number="1503">FG Angewandte Physik und Halbleiterspektroskopie</collection>
  </doc>
  <doc>
    <id>12472</id>
    <completedYear/>
    <publishedYear>2014</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>13654</pageFirst>
    <pageLast>13661</pageLast>
    <pageNumber/>
    <edition/>
    <issue>16</issue>
    <volume>2014</volume>
    <type>articler</type>
    <publisherName/>
    <publisherPlace/>
    <creatingCorporation/>
    <contributingCorporation/>
    <belongsToBibliography>0</belongsToBibliography>
    <completedDate>2014-10-28</completedDate>
    <publishedDate>--</publishedDate>
    <thesisDateAccepted>--</thesisDateAccepted>
    <title language="eng">A density functional theory study of catalytic sites for oxygen reduction in Fe/N/C catalysts used in H2/O2 fuel cells</title>
    <abstract language="eng">The oxygen reduction catalytic activity of carbon-supported FeN4 moieties bridging micropores between two graphene sheets was investigated by density functional theory (DFT). Based on the FeN2+2/C structure proposed earlier by our group, two types of FeN2+2/C structures were considered: one mostly planar and one in which the Fe ion is significantly displaced out of the graphitic plane. A structure in which the FeN4 moiety is embedded in an extended graphene sheet (FeNpyri4/C) was also considered. In addition, we have investigated the influence of an axial pyridine group approaching the Fe centre. The formation energy is lowest for the planar FeN2+2/C structure. The overall downhill behaviour of the relative free energy vs. the reaction step suggests that most structures have catalytic activity near zero potential. This conclusion is further supported by calculations of the binding energies of adsorbed O2 and H2O and of the O–O bond lengths of adsorbed O2 and OOH. The side-on interaction of adsorbed O2 is preferred over the end-on interaction for the three basic structures without the axial pyridine. The pyridine coordination produces a stronger binding of O2 for the planar FeN2+2/C and the FeNpyri4/C structures as well as a dominant end-on interaction of O2. The energy levels of the planar FeN2+2/C structure with and without the pyridine ligand are nearly equal for iron spin states S = 1 and S = 2, suggesting that both configurations are formed with similar concentration during the preparation process, as also previously found for two of the iron sites by Mössbauer spectroscopy experiments.</abstract>
    <parentTitle language="eng">Physical Chemistry Chemical Physics</parentTitle>
    <identifier type="doi">10.1039/C3CP55331K</identifier>
    <identifier type="issn">1463-9076</identifier>
    <identifier type="issn">1463-9084</identifier>
    <enrichment key="BTU">an der BTU erstellt / created at BTU</enrichment>
    <author>
      <firstName>Csaba E.</firstName>
      <lastName>Szakacs</lastName>
    </author>
    <submitter>
      <firstName>Karsten</firstName>
      <lastName>Henkel</lastName>
    </submitter>
    <author>
      <firstName>Michel</firstName>
      <lastName>Lefèvre</lastName>
    </author>
    <author>
      <firstName>Ulrike Ingrid</firstName>
      <lastName>Kramm</lastName>
    </author>
    <author>
      <firstName>Jean-Pol</firstName>
      <lastName>Dodelet</lastName>
    </author>
    <author>
      <firstName>François</firstName>
      <lastName>Vidal</lastName>
    </author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>density functional theory (DFT)</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>iron-based catalyst</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>iron−nitrogen−carbon catalyst</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>non-noble metal catalyst</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>oxygen reduction reaction (ORR)</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>polymer electrolyte membrane fuel cell (PEM-FC)</value>
    </subject>
    <collection role="old_institute" number="01005">LS Angewandte Physik / Sensorik</collection>
    <collection role="institutes" number="1503">FG Angewandte Physik und Halbleiterspektroskopie</collection>
  </doc>
</export-example>
