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

Platinum is the most widely used and best performing sole element for catalysing 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 7 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 which 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 substochiometric oxide component is identified. The oxide...