کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5424315 | 1395819 | 2009 | 7 صفحه PDF | دانلود رایگان |
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 â0.75Â 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(1Â 1Â 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 CC hydrogenation of EpB to 1-epoxybutane are consistent with computed electronic (ligand) and bifunctional effects.
Journal: Surface Science - Volume 603, Issue 4, 15 February 2009, Pages 690-696