Supported Pd-Cu catalysts prepared from bimetallic organo-metallic complexes: relation between surface composition measured by Ion Scattering and reactivity

AbstractEnergy-angle distributions of low-energy inert-gas ions scattered from surfaces provide information about surface composition and structure. We have measured energy spectra of He+ scattered from an Al71Pd20Mn9 quasicrystal, which was oriented perpendicular to the 5-fold axis, along various azimuthal directions. Strong scattering signals are seen from Al and Pd, but only a weak Mn signal is observed. From measurements made of He+ at an oblique angle of incidence scattered in the forward direction, we observe a 72° periodicity in the azimuthal dependence of the scattering signal intensity from Al surface atoms. The effect arises from shadowing effects involving neighboring surface atoms and provides direct evidence that Al surface atoms exist in a local environment with 5-fold symmetry. In addition, measuring the variation of the signal intensity with incidence angle provides information about neighboring atom distances, which compare favorably with a model of the quasicrystal surface derived from the bulk structure.

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Surface composition of perovskite-type materials studied by Low Energy Ion Scattering (LEIS)

Solid State Ionics ◽

10.1016/j.ssi.2013.09.010 ◽

2014 ◽

Vol 262 ◽

pp. 893-896 ◽

Cited By ~ 80

Author(s):

John Druce ◽

Tatsumi Ishihara ◽

John Kilner

Keyword(s):

Surface Composition ◽

Low Energy ◽

Ion Scattering ◽

Low Energy Ion Scattering ◽

Perovskite Type

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The hydrogenation of triglycerides using supported alloy catalysts. II. Silica-supported Pd-Cu catalysts

Journal of Chemical Technology & Biotechnology ◽

10.1002/jctb.280500109 ◽

2007 ◽

Vol 50 (1) ◽

pp. 81-90 ◽

Cited By ~ 1

Author(s):

J. D. Parry ◽

J. M. Winterbottom

Keyword(s):

Cu Catalysts ◽

Alloy Catalysts ◽

Supported Pd

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Phase transformations in silica-supported Pd–Cu catalysts during reduction in hydrogen

Journal of Catalysis ◽

10.1016/j.jcat.2013.02.008 ◽

2013 ◽

Vol 301 ◽

pp. 112-115 ◽

Cited By ~ 9

Author(s):

M. Bonarowska ◽

W. Juszczyk ◽

Z. Karpiński

Keyword(s):

Phase Transformations ◽

Cu Catalysts ◽

Supported Pd

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Multitechnique surface spectroscopic studies of plasma-modified polymers I: H2O/Ar plasma-modified polymethylmethacrylates

Journal of Materials Research ◽

10.1557/jmr.1987.0117 ◽

1987 ◽

Vol 2 (1) ◽

pp. 117-131 ◽

Cited By ~ 34

Author(s):

Thomas J. Hook ◽

Joseph A. Gardella ◽

Lawrence Salvati

Keyword(s):

Photoelectron Spectroscopy ◽

Surface Composition ◽

Polymer Surface ◽

Spectroscopic Studies ◽

Rf Plasma ◽

Ion Scattering ◽

Modified Polymers ◽

Low Energy Ion Scattering ◽

Structural Differences ◽

Limited Depth

Results from x-ray photoelectron spectroscopy (XPS or ESCA), low-energy ion scattering spectrometry (LEIS or ISS); and Fourier transform infrared spectroscopy (FTIR) analyses are presented for unmodified and modified poly (methylmethacrylate) (PMMA) polymer films. Analysis of the unmodified PMMA polymers (isotactic, syndiotactic, and atactic) via ESCA, ISS, and FTIR, established the surface composition, bonding, and functionality before the modification was employed. An rf-plasma glow discharge created from an Ar/H2O gas mixture at different exposure times and power levels was used to treat the polymer surface. Subsequent ESCA, ISS, and FTIR analyses of these modified PMMA's show the effects of surface modification in terms of a model of structural differences, over a limited depth (50–100 Å). The composition and functionality changes of the resulting surfaces are discussed with respect to proposed mechanisms of the plasma reaction and differences in tacticity of the reactant. A two-step reaction mechanism involving reactive decarboxylation/reduction followed by H2O adsorption is proposed to understand the spectroscopic results.

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