Journal article
Direct observation of the dealloying process of a platinum–yttrium nanoparticle fuel cell cathode and its oxygenated species during the oxygen reduction reaction
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 nderstanding of both their activity and stability.
Herein, size-selected 9 nm PtxY anoparticles 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.
Language: | English |
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Publisher: | The Royal Society of Chemistry |
Year: | 2015 |
Pages: | 28121-28128 |
ISSN: | 14639084 and 14639076 |
Types: | Journal article |
DOI: | 10.1039/c5cp00283d |
ORCIDs: | Stephens, Ifan , Chorkendorff, Ib and 0000-0003-2597-8112 |