Methanol Reaction on Pt-Au Clusters on TiO2(110): Methoxy-Induced Diffusion of Pt

    Authors

    S. A. Tenney; S. I. Shah; H. Yan; B. A. Cagg; M. S. Levine; T. S. Rahman;D. A. Chen

    Comments

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    Abbreviated Journal Title

    J. Phys. Chem. C

    Keywords

    GOLD-PLATINUM NANOPARTICLES; PT-RH(100) ALLOY SURFACE; METAL-SUPPORT; INTERACTIONS; DENSITY-FUNCTIONAL THEORY; ADSORBATE-INDUCED CHANGES; SINGLE-CRYSTAL SURFACES; AUGMENTED-WAVE METHOD; O BOND SCISSION; BIMETALLIC SURFACES; CHEMICAL-PROPERTIES; Chemistry, Physical; Nanoscience & Nanotechnology; Materials Science, ; Multidisciplinary

    Abstract

    The reaction of methanol on Pt-Au bimetallic clusters on TiO2(110) with varying bulk Au fractions has been studied by temperature programmed desorption (TPD) experiments and density functional theory (DFT) calculations. The bimetallic clusters with bulk Au fractions greater than 50% have surfaces that are 100% Au, but these Pt-Au clusters exhibit activity for methanol decomposition that is characteristic of Pt rather than Au; while methanol reaction on pure Pt clusters forms CO as a major product, reaction on pure Au clusters produces formaldehyde. Furthermore, as the bulk Pt concentration is decreased from 100 to 50% in the Pt-Au clusters, the CO yield decreases by only similar to 25%. This behavior is consistent with methoxy-induced diffusion of Pt to the surface of the clusters in order to form strong Pt-methoxy bonds. DFT studies indicate that it is thermodynamically favorable for Pt to diffuse to the surface and bind to the methoxy adsorbate. Specifically, DFT calculations show that the methoxy intermediate bound to a single Pt atom in a Au monolayer on Pt(111) is more thermodynamically stable than methoxy bound to a Au monolayer modified by underlying Pt(111). Although extensive changes in activity due to bimetallic interactions are not observed, the peak temperature for CO desorption decreases by 25 K as the Pt fraction is decreased from 100% to 25%, and the selectivity for methane is higher on bimetallic clusters than on either of the pure metals.

    Journal Title

    Journal of Physical Chemistry C

    Volume

    117

    Issue/Number

    51

    Publication Date

    1-1-2013

    Document Type

    Article

    Language

    English

    First Page

    26998

    Last Page

    27006

    WOS Identifier

    WOS:000329331300017

    ISSN

    1932-7447

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