Zobrazeno 1 - 10
of 12
pro vyhledávání: '"Stefan Helmly"'
Autor:
K. Andreas Friedrich, Michael Handl, Tobias Morawietz, Ines Galm, Renate Hiesgen, Stefan Helmly
Publikováno v:
Membranes, Vol 2, Iss 4, Pp 783-803 (2012)
The conductivity of fuel cell membranes as well as their mechanical properties at the nanometer scale were characterized using advanced tapping mode atomic force microscopy (AFM) techniques. AFM produces high-resolution images under continuous curren
Externí odkaz:
https://doaj.org/article/96c12b1b57a543faa317f0d51ced0c0a
Autor:
Mathias Schulze, Daniel Garcia Sanchez, K. Andreas Friedrich, Tiziana Ruiu, Indro Biswas, Stefan Helmly
Publikováno v:
Journal of Power Sources. 352:42-55
Water management represents one of the main challenges in the design and operation of Polymer Electrolyte Fuel Cells (PEFCs). Besides performance, the water level also affects the durability of the cell. Understanding the degradation processes is of
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::68350c6e28072633e1ddbf977e400f95
https://doi.org/10.1016/j.jpowsour.2017.03.057
https://doi.org/10.1016/j.jpowsour.2017.03.057
Publikováno v:
Electrocatalysis. 8:501-508
Based on recent theoretical studies, we designed a multistep experimental protocol to understand the impact of environmental conditions around Pt nanodeposits on Membrane chemical degradation. The first experiment probes the local potential at a Pt m
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::ae804bcdde82b3e199a98427dfef6b95
https://doi.org/10.1007/s12678-017-0353-2
https://doi.org/10.1007/s12678-017-0353-2
Autor:
K. Andreas Friedrich, Michael Handl, Mathias Schulze, Krishan Talukdar, Jürgen Kraut, Daniel Garcia Sanchez, Renate Hiesgen, Stefan Helmly
This study presents innovative concepts for improving performance of membrane electrode assemblies (MEAs) prepared by the dry-spraying method introduced by the German Aerospace center (DLR). Dry-spraying is a time and cost effective method that invol
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::e8b53970db639b423d4725053d56052e
https://elib.dlr.de/130522/
https://elib.dlr.de/130522/
Publikováno v:
ECS Transactions. 58:1085-1096
In this work we investigated Nafion® 211 polymer electrolyte membranes after 1600 h operation at open circuit voltage. With scanning electron microscopy (SEM) platinum deposition was identified inside the membrane. By investigation of cross sections
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::a348d430d3b1faf9861764fdb9d649e5
https://doi.org/10.1149/05801.1085ecst
https://doi.org/10.1149/05801.1085ecst
Autor:
Philipp Lettenmeier, Fabian Burggraf, Rami Abouatallah, Rainey Wang, Stefan Helmly, Tobias Morawietz, Josef Kallo, Svenja Kolb, Aldo Saul Gago, Kaspar Andreas Friedrich, Renate Hiesgen
High efficiencies, wide operation range and rapid response time have motivated the recent interest in proton exchange membrane (PEM) electrolysis for hydrogen generation with surplus electricity. However, degradation at high current densities and the
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::2f6828503a90a151560de1954cd20764
https://elib.dlr.de/104474/
https://elib.dlr.de/104474/
Autor:
Xiao-Zi Yuan, Stefan Helmly, Renate Hiesgen, Tobias Morawietz, K. Andreas Friedrich, Haijiang Wang
Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to investigate platinum (Pt) deposition in the membrane of degraded proton exchange membrane fuel cells (PEMFCs). This study focuses on Pt distribution and microscopic asp
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::43375ae11202890e38534a9a4ae392e6
https://nrc-publications.canada.ca/eng/view/object/?id=2b05cac9-bfe9-498e-a33a-452ffa47870a
https://nrc-publications.canada.ca/eng/view/object/?id=2b05cac9-bfe9-498e-a33a-452ffa47870a
In this study, the role of Pt concentration and distribution in the membrane on ionomer degradation was investigated. Nafion® membranes were impregnated with different mass fraction of Pt via ion-exchange and operated as membrane electrode assemblie
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::689f7334dd33f547d61e662dbcdd16a3
https://doi.org/10.1149/05801.0969ecst
https://doi.org/10.1149/05801.0969ecst
Autor:
Xiao-Zi Yuan, Renate Hiesgen, Haijiang Wang, K. Andreas Friedrich, Stefan Helmly, Ines Wehl, Mathias Schulze, Andrea Haug
The ageing of microporous layers (MPL) of fuel cell gas diffusion layers has been quantitavely analyzed using a special atomic force microscopy technique, namely the so-called HarmoniX technique. From the change of mean adhesion force under dry and w
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::60f5101c44916d12b7d8fa1a11657a85
https://elib.dlr.de/71418/
https://elib.dlr.de/71418/
Autor:
Haijiang Wang, Mathias Schulze, Ines Wehl, Xiao-Zi Yuan, K. Andreas Friedrich, Andrea Haug, Alexander Bauder, Renate Hiesgen, Stefan Helmly
In this contribution, the possibilities and limits of atomic force microscopy (AFM) for investigation of fuel cell component degradation are evaluated. In particular the adhesion force and dissipation energy of the surface measured by a material sens
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::e48f0623a5063c2fc382058661961d36
https://doi.org/10.1016/j.jelechem.2011.07.014
https://doi.org/10.1016/j.jelechem.2011.07.014