Effects of $\gamma $-Al$_{\mathrm{\mathbf{2}}}$O$_{\mathrm{\mathbf{3}}}$ Support on the Morphology and Electronic Structure of Pt Nanoparticles

ORAL

Abstract

We have studied the effects of pristine and hydroxylated $\gamma $-Al$_{\mathrm{2}}$O$_{\mathrm{3}}$(110) support on the morphology and electronic structure of clean and H-covered Pt nanoparticles (NP) containing 22 and 44 atoms (Pt$_{\mathrm{22\thinspace }}$and Pt$_{\mathrm{44}})$ using density functional theory (DFT) based calculations. We find a morphology change from 3 dimensional (3D) to a bi-planar shape for Pt$_{\mathrm{22}}$ upon adsorption on pristine and partially hydroxylated $\gamma $-Al$_{\mathrm{2}}$O$_{\mathrm{3}}$(110) surface. This shape change is not found for higher hydroxylation coverage (0.325 monolayer (ML) and higher) or for Pt$_{\mathrm{44}}$, indicating that the aforementioned effect is size and OH coverage dependent. Furthermore, the relative position of the d-band center of the unoccupied orbitals of the nanoparticles is sensitive to the presence of the support and the extent to which it is hydroxylated. A competing and even dominating effect on the electronic structure of the nanoparticles comes from adsorbed hydrogen. At higher temperatures when the effect of adsorbates is minimal, the shift in the d-band center of the unoccupied orbitals is found to correlate with the extent of metal-support interaction In the light of these results, we conclude that an accurate description of the local environment of nanoparticles (support, hydroxylation of the support, adsorbed hydrogen) is necessary in order to understand the preferred shape and electronic structure of these nanoparticles.

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Authors

  • Ghazal Shafai

    University of Central Florida

  • Richard Longland

    University of Tennessee, Knoxville, University of Alabama at Birmingham, Rutgers, The State University of New Jersey, Florida Intl Univ, Christopher Newport University, Jefferson Laboratory, University of North Georgia, Dahlonega GA 30597, Oak Ridge National Laboratory, Oak Ridge, TN 37831, Austin Peay State University department of physics and astronomy, Laboratoire des Verres et et Ceramiques, Institute des Sciences chimiques de Rennes, Austin Peay State University Department of Physics and Astronomy, Université de Rennes, Lehigh University, Austin Peay State University, University of Alabama, Oak Ridge National Laboratory, Auburn University, Auburn, AL, Purdue University, West Lafayette, IN, Queen's University Belfast, Belfast, United Kingdom, Harvard Smithsonian Center for Astrophysics, Boston, MA, Francis Marion University, Auburn University, Lawrence Berkeley National Laboratory, University of California, Davis, University of Alabama Huntsville, Oak Ridge National Lab, Univ of Tennessee, Knoxville, Oak Ridge National Lab, Univ of Tennessee, Knoxville, ITEP, Moscow, Baylor University, Saint Louis University, Louisiana State Univ - Baton Rouge, University of Chicago, Oak Ridge National Laboratory , Oak Ridge TN 37831, American Superconductor Corp., Westborough, MA 01581, USA, Tsinghua University, LBNL, Vanderbilt University, Laboratoire Aime Cotton, CNRS/Universite Paris-Sud/ENS-Cachan, Orsay France, Drake University, Des Moines, IA, University of Central Florida, University of South Alabama, North Carolina Central University

  • Talat S. Rahman

    University of Central Florida