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Theoretical and experimental studies of Ag-Pt interactions for supported Ag-Pt bimetallic catalysts |
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| Authors: | Melanie T Schaal |
| Institution: | a Department of Chemical Engineering, University of South Carolina, 2C02 Swearingen Engineering Center, 301 Main Street, Columbia, SC 29208, USA b Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 S. 33rd Street, Philadelphia, PA 19104-6393, USA c Department of Chemical and Biological Engineering, University of Colorado at Boulder, 424 UCB, Room ECCH 101, Boulder, CO 80309-0424, USA |
| Abstract: | The electronic structure and chemical properties of catalysts prepared by the electroless deposition (ED) of Ag onto Pt/SiO2 were studied using a combination of X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations. XPS studies revealed a negative shift (up to −0.75 eV) in the Ag 3d binding energy (BE) relative to bulk Ag. Both the magnitude and direction of the shift are consistent with DFT calculations of model Ag/Pt(1 1 1) surfaces. DFT calculations have also been employed to study the adsorption of two probe molecules, carbon monoxide and 1-epoxy-3-butene (EpB), on the model surfaces. Combined with previously published reports, the results presented here suggest that (1) the AgPt/SiO2 catalysts that are most active for hydrogenation of the EpB olefin function consist of an adlayer of Ag on Pt rather than a surface or bulk alloy and that (2) the higher activity and selectivity of ED-prepared Ag-Pt/SiO2 catalysts for C C hydrogenation of EpB to 1-epoxybutane are consistent with computed electronic (ligand) and bifunctional effects. |
| Keywords: | X-ray photoelectron spectroscopy Ab-initio quantum chemical methods and calculations Silver Platinum Bimetallic surfaces Electronic effect Core level shifts |
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