Issue 42, 2015

Direct observation of the dealloying process of a platinum–yttrium nanoparticle fuel cell cathode and its oxygenated species during the oxygen reduction reaction

Abstract

Size-selected 9 nm PtxY nanoparticles have recently shown an outstanding catalytic activity for the oxygen reduction reaction, representing a promising cathode catalyst for proton exchange membrane fuel cells (PEMFCs). Studying their electrochemical dealloying is a fundamental step towards the understanding of both their activity and stability. Herein, size-selected 9 nm PtxY nanoparticles have been deposited on the cathode side of a PEMFC specifically designed for in situ ambient pressure X-ray photoelectron spectroscopy (APXPS). The dealloying mechanism was followed in situ for the first time. It proceeds through the progressive oxidation of alloyed Y atoms, soon leading to the accumulation of Y3+ cations at the cathode. Acid leaching with sulfuric acid is capable of accelerating the dealloying process and removing these Y3+ cations which might cause long term degradation of the membrane. The use of APXPS under near operating conditions allowed observing the population of oxygenated surface species as a function of the electrochemical potential. Similar to the case of pure Pt nanoparticles, non-hydrated hydroxide plays a key role in the ORR catalytic process.

Graphical abstract: Direct observation of the dealloying process of a platinum–yttrium nanoparticle fuel cell cathode and its oxygenated species during the oxygen reduction reaction

Supplementary files

Article information

Article type
Paper
Submitted
16 Jan 2015
Accepted
04 Mar 2015
First published
13 Mar 2015

Phys. Chem. Chem. Phys., 2015,17, 28121-28128

Direct observation of the dealloying process of a platinum–yttrium nanoparticle fuel cell cathode and its oxygenated species during the oxygen reduction reaction

P. Malacrida, H. G. Sanchez Casalongue, F. Masini, S. Kaya, P. Hernández-Fernández, D. Deiana, H. Ogasawara, I. E. L. Stephens, A. Nilsson and I. Chorkendorff, Phys. Chem. Chem. Phys., 2015, 17, 28121 DOI: 10.1039/C5CP00283D

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