Issue 14, 2012
From the journal:

Physical Chemistry Chemical Physics

Probing platinum degradation in polymer electrolyte membrane fuel cells by synchrotron X-ray microscopy†

Viatcheslav Berejnov,a   Zulima Martin,b   Marcia West,a   Sumit Kundu,c   Dmitri Bessarabov,d   Jürgen Stumper,c   Darija Susacc  and  Adam P. Hitchcock*a  

* Corresponding authors

a Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON, Canada
E-mail: aph@mcmaster.ca

b Environmental Energy Technology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA

c Automotive Fuel Cell Cooperation Corp., 9000 Glenlyon Parkway, Burnaby, BC, Canada

d North-West University, Hydrogen Infrastructure Center of Competence, HySA, Private Bag X6001, Potchefstroom, South Africa

Abstract

Synchrotron-based scanning transmission X-ray spectromicroscopy (STXM) was used to characterize the local chemical environment at and around the platinum particles in the membrane (PTIM) which form in operationally tested (end-of-life, EOL) catalyst coated membranes (CCMs) of polymer electrolyte membrane fuel cells (PEM-FC). The band of metallic Pt particles in operationally tested CCM membranes was imaged using transmission electron microscopy (TEM). The cathode catalyst layer in the beginning-of-life (BOL) CCMs was fabricated using commercially available catalysts created from Pt precursors with and without nitrogen containing ligands. The surface composition of these catalyst powders was measured by X-ray Photoelectron Spectroscopy (XPS). The local chemical environment of the PTIM in EOL CCMs was found to be directly related to the Pt precursor used in CCM fabrication. STXM chemical mapping at the N 1s edge revealed a characteristic spectrum at and around the dendritic Pt particles in CCMs fabricated with nitrogen containing Pt-precursors. This N 1s spectrum was identical to that of the cathode and different from the membrane. For CCM samples fabricated without nitrogen containing Pt-precursors the N 1s spectrum at the Pt particles was indistinguishable from that of the adjacent membrane. We interpret these observations to indicate that nitrogenous ligands in the nitrogen containing precursors, or decomposition product(s) from that source, are transported together with the dissolved Pt from the cathode into the membrane as a result of the catalyst degradation process. This places constraints on possible mechanisms for the PTIM band formation process.

Graphical abstract: Probing platinum degradation in polymer electrolyte membrane fuel cells by synchrotron X-ray microscopy

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Article information

DOI
https://doi.org/10.1039/C2CP40338B
Article type
Paper
Submitted
29 Nov 2011
Accepted
21 Feb 2012
First published
21 Feb 2012

Phys. Chem. Chem. Phys., 2012,14, 4835-4843

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Probing platinum degradation in polymer electrolyte membrane fuel cells by synchrotron X-ray microscopy

V. Berejnov, Z. Martin, M. West, S. Kundu, D. Bessarabov, J. Stumper, D. Susac and A. P. Hitchcock, Phys. Chem. Chem. Phys., 2012, 14, 4835 DOI: 10.1039/C2CP40338B

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