| AVS 57th International Symposium & Exhibition | |
| Energy Frontiers Topical Conference | Thursday Sessions |
| Session EN+AS-ThM |
| Session: | Surface and Interface Analysis of Materials for Energy |
| Presenter: | A. Patel, University of New Mexico |
| Authors: | A. Patel, University of New Mexico K. Artyushkova, University of New Mexico P. Atanassov, University of New Mexico A. Young, Ballard Power Systems, Canada M. Dutta, Ballard Power Systems, Canada Z. Ahmad, Ballard Power Systems, Canada V. Colbow, Ballard Power Systems, Canada S. Wessel, Ballard Power Systems, Canada |
| Correspondent: | Click to Email |
Understanding the chemical structure and morphology of Pt electrocatalysts and their supports, and linking these parameters to electrocatalytic activity, corrosion stability and overall performance of the fuel cell is essential for elucidation of failure mechanisms and optimization of support properties. The strategy presented in this work can be viewed as universal methodology that allows correlation between multiple variables relevant to fuel cell technology.
In this work we have investigated the performance and corrosion stability of Pt electrocatalysts supported on different carbon supports in order to understand the effect of the carbon support on catalyst degradation. Low surface area (LSA), mid-range surface area (MSA), high surface area (HSA) and heat treated (to induce graphitization) high surface area carbons were extensively studied and characterized.
X-ray Photoelectron Spectroscopy (XPS) has been chosen to obtain information on graphiticity and amount of surface oxides on carbon supports. The ability to discriminate between different carbon chemical environments, not just elemental compositions, is one of the primary advantages of XPS in the characterization of carbon corrosion.
Morphological properties such as size of particles, size of particles agglomerates, surface area, roughness and porosity are equally contributive to corrosion process. Digital Image Processing (DIP) can be applied to SEM and TEM images to extract statistical parameters, such as roughness, particle size distributions, shape parameters, texture parameters, which all are related to morphology of carbon blacks.
Performance and durability of Pt electrocatalysts supported on various carbon blacks were evaluated extensively electrochemically to provide activity from rotating disk electrode measurements, capacitance and photon resistance from Electrode Impedance Spectroscopy, voltage degradation rates, effective platinum surface area and kinetic losses.
This multi-analytical approach provides a large set of variables (structural, physical and microscopic properties) which must be related to corrosion and performance behaviour of carbon blacks. Multivariate statistical methods of data analysis (MVA) become, thus, of critical importance in structure-to-property relationship modeling. Principal Component Analysis (PCA) is used as a visualization tool to find samples which are globally correlated or anti-correlated, and to facilitate visualization of the variables responsible for the correlations. Through this methodology, we have determined which set of structural and morphological parameters are responsible for durable and active electrocatalyst.