skip to main content

DOE PAGESDOE PAGES

This content will become publicly available on August 15, 2018

Title: 3D Analysis of Fuel Cell Electrocatalyst Degradation on Alternate Carbon Supports

Understanding the mechanisms associated with Pt/C electrocatalyst degradation in proton exchange membrane fuel cell (PEMFC) cathodes is critical for the future development of higher-performing materials; however, there is a lack of information regarding Pt coarsening under PEMFC operating conditions within the cathode catalyst layer. We report a direct and quantitative 3D study of Pt dispersions on carbon supports (high surface area carbon (HSAC), Vulcan XC-72, and graphitized carbon) with varied surface areas, graphitic character, and Pt loadings ranging from 5 to 40 wt %. This is accomplished both before and after catalyst-cycling accelerated stress tests (ASTs) through observations of the cathode catalyst layer of membrane electrode assemblies. Electron tomography results show Pt nanoparticle agglomeration occurs predominantly at junctions and edges of aggregated graphitized carbon particles, leading to poor Pt dispersion in the as-prepared catalysts and increased coalescence during ASTs. Tomographic reconstructions of Pt/HSAC show much better initial Pt dispersions, less agglomeration, and less coarsening during ASTs in the cathode. However, a large loss of the electrochemically active surface area (ECSA) is still observed and is attributed to accelerated Pt dissolution and nanoparticle coalescence. Moreover, a strong correlation between Pt particle/agglomerate size and measured ECSA is established and is proposed asmore » a more useful metric than average crystallite size in predicting degradation behavior across different catalyst systems.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [1] ;  [1] ;  [2] ; ORCiD logo [2] ; ORCiD logo [2] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Report Number(s):
LA-UR-17-27245
Journal ID: ISSN 1944-8244; TRN: US1800678
Grant/Contract Number:
AC52-06NA25396; AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
ACS Applied Materials and Interfaces
Additional Journal Information:
Journal Volume: 9; Journal Issue: 35; Journal ID: ISSN 1944-8244
Publisher:
American Chemical Society (ACS)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Fuel Cell Technologies Office (EE-3F)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; energy sciences; fuel cells; catalysts; electrocatalysts; 3D; electrochemically active surface area; electron tomography; graphitized carbon; PEM fuel cells
OSTI Identifier:
1414157
Alternate Identifier(s):
OSTI ID: 1414700