AVS 60th International Symposium and Exhibition
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP29
Adsorbate-induced Atomic Segregation Phenomena and Morphological Stability of Size- and Shape-Selected Octahedral PtNi Nanoparticles

Tuesday, October 29, 2013, 6:00 pm, Room Hall B

Session: Surface Science Poster Session
Presenter: M. Ahmadi, University of Central Florida
Authors: M. Ahmadi, University of Central Florida
F. Behafarid, University of Central Florida
C. Cui, Technical University Berlin, Germany
P. strasser, Technical University Berlin, Germany
B. Roldan Cuenya, University of Central Florida
Correspondent: Click to Email
A study of the morphological and chemical stability of shape-selected octahedral PtNi nanoparticles (NPs) supported on highly-oriented pyrolytic graphite (HOPG) is presented. In situ X-ray photoelectron spectroscopy (XPS), ex situ atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements were used to monitor atomic segregation phenomena in PtNi NPs under vacuum, H2, and O2 atmospheres. The initial oxidation state of the as-prepared NPs was found to play a pivotal role in the final surface composition of the NPs after the different thermal treatments. In particular, for these ex-situ synthesized NPs, Ni segregation to the NP surface was observed in all environments until all NiOx species were reduced. Enhanced Ni surface segregation was observed in the presence of oxygen, while Pt surface segregation took place in hydrogen and vacuum above 270°C.