An atomic X-ray absorption fine structure study of the influence of hydrogen chemisorption and support on the electronic structure of supported Pt particles |
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| Authors: | Ramaker DE van Dorssen GE Mojet BL Koningsberger DC |
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| Affiliation: | (1) Department of Chemistry and Materials Science Institute, George Washington University, Washington, DC 20052, USA;(2) Department of Inorganic Chemistry and Catalysis, Debye Institute, Utrecht University, PO Box 80083, 3508 TB Utrecht, The Netherlands |
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| Abstract: | The physical principles of atomic XAFS (AXAFS) are presented along with important details on how to isolate the AXAFS contribution
from the experimental XAFS data. Intuitive illustrations are given showing how various interactions of the absorber atom with
its neighbours influence the AXAFS contribution. Hydrogen chemisorbed on the surface of the supported metal particles is shown
to have a strong influence on the amplitude of the Fourier transform AXAFS peak. The effect of the support (with different
amounts and types of charge compensating ions (H+, K+), different Si/Al ratio and extra-framework Al) on the experimental AXAFS spectra of Pt dispersed in zeolites (LTL,Y) and
on flat supports (Al2O3–SiO2, MgO–Al2O3) are summarised. It is shown that the essence of the metal–support interaction, as revealed in the AXAFS, is a shift in the
ionisation potential of the valence d-orbital electrons brought about by the polarisation induced primarily by the changing
charge on the support oxygen atoms.
This revised version was published online in June 2006 with corrections to the Cover Date. |
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| Keywords: | atomic XAFS spectroscopy supported platinum catalysts metal– support interaction Pt electronic structure hydrogen chemisorption particle size effects |
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