Hiesgen, Renate and Wehl, Ines and Aleksandrova, Elena and Roduner, Emil and Bauder, Alexander and Friedrich, K. Andreas (2010) Nanoscale properties of polymer fuel cell materials - A selected review. International Journal of Energy Research, 34, pp. 1223-1238. Wiley. doi: 10.1002/er.1661.
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Abstract
The properties of the components of a membrane electrode assembly in a polymer electrolyte fuel cell (PEFC) determine its efficiency and performance. This paper aims at demonstrating the importance of nanoscale properties of PEFC membranes and electrodes and discussing the information obtained by various experimental techniques. The nanostructure and conductivity of freshly prepared as well as artificially degraded Nafion membranes and Pt/C electrodes are investigated by contact atomic force microscopy (AFM), conductive AFM, pulsed force mode (PFM)-AFM, in situ scanning tunnelling microscopy (STM), and scanning electron microscopy. The different techniques can provide complementary information on structure and conductivity. With in situ STM on Pt catalyst covered graphite, a layer of very small Pt particles between the catalyst particles is imaged, which is probably not visible with TEM and can explain a systematic discrepancy between TEM and XRD in particle size distribution. Conductive AFM is used to investigate the conductivity of Nafion. The images show a quite inhomogeneous distribution of current at the surface. The percentage of conductive surface increases with humidity, but regions without any current still present up to 80% of relative humidity (RH). Comparison with PFM-AFM images, where differences in adhesion forces are measured, indicates that hydrophobic regions are present at the surface with comparable dimensions, which are attributed to non-conductive PTFE-like polymer backbone. The changes in hydrophilic and hydrophobic parts after artificial degradation by plasma etching in air plasma can be imaged by PFM. High-resolution current images of the membrane were used to directly compare the measured nanostructure of the single conductive channels with model predictions from the literature. Recent models in the literature propose the formation of water-filled inverted micelles, with a mean diameter of 2.4 nm, and their agglomeration into clusters agrees well with the current images
Item URL in elib: | https://elib.dlr.de/66708/ | ||||||||||||||||||||||||||||
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Document Type: | Article | ||||||||||||||||||||||||||||
Title: | Nanoscale properties of polymer fuel cell materials - A selected review | ||||||||||||||||||||||||||||
Authors: |
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Date: | October 2010 | ||||||||||||||||||||||||||||
Journal or Publication Title: | International Journal of Energy Research | ||||||||||||||||||||||||||||
Refereed publication: | Yes | ||||||||||||||||||||||||||||
Open Access: | No | ||||||||||||||||||||||||||||
Gold Open Access: | No | ||||||||||||||||||||||||||||
In SCOPUS: | Yes | ||||||||||||||||||||||||||||
In ISI Web of Science: | Yes | ||||||||||||||||||||||||||||
Volume: | 34 | ||||||||||||||||||||||||||||
DOI: | 10.1002/er.1661 | ||||||||||||||||||||||||||||
Page Range: | pp. 1223-1238 | ||||||||||||||||||||||||||||
Publisher: | Wiley | ||||||||||||||||||||||||||||
Status: | Published | ||||||||||||||||||||||||||||
Keywords: | Niedertemperatur Brennstoffzellen; polymer membran, degradation | ||||||||||||||||||||||||||||
HGF - Research field: | Energy | ||||||||||||||||||||||||||||
HGF - Program: | Efficient Energy Conversion (old) | ||||||||||||||||||||||||||||
HGF - Program Themes: | E EV - Energy process technology (old) | ||||||||||||||||||||||||||||
DLR - Research area: | Energy | ||||||||||||||||||||||||||||
DLR - Program: | E EV - Energy process technology | ||||||||||||||||||||||||||||
DLR - Research theme (Project): | E - Elektrochemische Prozesse (old) | ||||||||||||||||||||||||||||
Location: | Stuttgart | ||||||||||||||||||||||||||||
Institutes and Institutions: | Institute of Engineering Thermodynamics > Electrochemical Energy Technology | ||||||||||||||||||||||||||||
Deposited By: | Friedrich, Prof.Dr. Kaspar Andreas | ||||||||||||||||||||||||||||
Deposited On: | 30 Nov 2010 14:56 | ||||||||||||||||||||||||||||
Last Modified: | 08 Mar 2018 18:38 |
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