Unraveling the Surface Chemistry and Structure in Highly Active Sputtered Pt3Y Catalyst Films for the Oxygen Reduction Reaction
Journal article, 2020

Platinum is the most widely used and best performing sole element for catalyzing the oxygen reduction reaction (ORR) in low-temperature fuel cells. Although recyclable, there is a need to reduce the amount used in current fuel cells for their extensive uptake in society. Alloying platinum with rare-earth elements such as yttrium can provide an increase in activity of more than seven times, reducing the amount of platinum and the total amount of catalyst material required for the ORR. As yttrium is easily oxidized, exposure of the Pt-Y catalyst layer to air causes the formation of an oxide layer that can be removed during acid treatment, leaving behind a highly active pure platinum overlayer. This paper presents an investigation of the overlayer composition and quality of Pt3Y films sputtered from an alloy target. The Pt3Y catalyst surface is investigated using synchrotron radiation X-ray photoelectron spectroscopy before and after acid treatment. A new substoichiometric oxide component is identified. The oxide layer extends into the alloy surface, and although it is not completely removed with acid treatment, the catalyst still achieves the expected high ORR activity. Other surface-sensitive techniques show that the sputtered films are smooth and bulk X-ray diffraction reveals many defects and high microstrain. Nevertheless, sputtered Pt3Y exhibits a very high activity regardless of the film's oxide content and imperfections, highlighting Pt3Y as a promising catalyst. The obtained results will help to support its integration into fuel cell systems.

materials science


platinum alloys

oxygen reduction reaction

fuel cell catalyst

X-ray spectroscopy

thin films



Rosemary Brown

Chalmers, Physics, Chemical Physics

Mykhailo Vorokhta

Charles University

Ivan Khalakhan

Charles University

Milan Dopita

Charles University

Thomas Vonderach

Technical University of Denmark (DTU)

Tomáš Skála

Charles University

Niklas Lindahl

University of Gothenburg, Department of Physics

Iva Matolínová

Charles University

Henrik Grönbeck

Chalmers, Physics, Chemical Physics

Konstantin M. Neyman

Catalan Institution for Research and Advanced Studies

University of Barcelona

Vladimír Matolín

Charles University

Björn Wickman

Chalmers, Physics, Chemical Physics

ACS Applied Materials & Interfaces

1944-8244 (ISSN) 1944-8252 (eISSN)

Vol. 12 4 4454-4462

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