Nanoparticle catalysts have garnered interest due to the high surface area and reactivity compared to bulk material. In particular, platinum nanoparticles are of interest because of the many reactions platinum can catalyze. However, the cost of noble metals is a driving force for the integration of other metals to the platinum nanoparticle to impart both improved activity and cost effectiveness. Core-shell structured platinum-metal (Pt-M, M=Fe, Co, Ni) have been extensively examined due to the potential as an alternative to traditional platinum nanoparticles for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells. Ordered Pt3M nanoparticles have also been studied due to the high ORR activity compared to pure platinum. However, in the presence of adsorbed oxygen, leaching of the alloy metal causes deformation of the structure at the surface. Understanding the surface and constructing a stable, high surface area nanoparticle is a crucial part of improving electrocatalytic material. By controlling the stimulus, appropriate surface reconstruction can be performed without degrading the nanoparticle. In this work, we observe the surface reconstruction of cubic Pt3Co nanoparticles under thermal stimulus in situ at atomic resolution. Energy dispersive x-ray spectroscopy shows the incorporation of silicon into the structure as the surface forms a platinum skin. We observe both time and temperature dependence for the reconstruction process.

In situ study of surface reconstruction of cubic Pt3Co nanoparticles under thermal stimulus using high resolution TEM

2019 Fall National Meeting

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