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Title: Imaging and microanalysis of thin ionomer layers by scanning transmission electron microscopy

Improved conditions for imaging and spectroscopic mapping of thin perfluorosulfonic acid (PFSA) ionomer layers in fuel cell electrodes by scanning transmission electron microscopy (STEM) have been investigated. These conditions are first identified on model systems of Nafion ionomer-coated nanostructured thin films and nanoporous Si. The optimized conditions are then applied in a quantitative study of the ionomer through-layer loading for two typical electrode catalyst coatings using electron energy loss and energy dispersive X-ray spectroscopy in the transmission electron microscope. The e-beam induced damage to the perfluorosulfonic acid (PFSA) ionomer is quantified by following the fluorine mass loss with electron exposure and is then mitigated by a few orders of magnitude using cryogenic specimen cooling and a higher incident electron voltage. Multivariate statistical analysis is also applied to the analysis of spectrum images for data denoising and unbiased separation of independent components related to the catalyst, ionomer, and support.
 [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [1] ;  [4] ;  [1] ;  [1] ;  [1]
  1. ORNL
  2. General Motors Corporation
  3. Clarkson University, Potsdam, NY
  4. French Atomic Energy Commission (CEA), Grenoble
Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the Electrochemical Society; Journal Volume: 161; Journal Issue: 10
Research Org:
Oak Ridge National Laboratory (ORNL); Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
Country of Publication:
United States