Journal
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Volume 17, Issue 42, Pages 28121-28128Publisher
ROYAL SOC CHEMISTRY
DOI: 10.1039/c5cp00283d
Keywords
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Funding
- Danish Council for Strategic Research's project NACORR [12-132695]
- Danish National Research Foundation's Center for Individual Nanoparticle Functionality [DNRF54]
- Joint Center for Artificial Photosynthesis Award [DE-SC0004993]
- Precursory Research for Embryonic Science and Technology (PRESTO), Japan Science and Technology Agency (JST)
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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.
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