The adsorption of CO,O2, and H2 on Pt(100)-(5×20) |
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Authors: | MA Barteau EI Ko RJ Madix |
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Institution: | Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA |
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Abstract: | The adsorption/desorption characteristics of CO, O2, and H2 on the Pt(100)-(5 × 20) surface were examined using flash desorption spectroscopy. Subsequent to adsorption at 300 K, CO desorbed from the (5×20) surface in three peaks with binding energies of 28, 31.6 and 33 kcal gmol?1. These states formed differently from those following adsorption on the Pt(100)-(1 × 1) surface, suggesting structural effects on adsorption. Oxygen could be readily adsorbed on the (5×20) surface at temperatures above 500 K and high O2 fluxes up to coverages of of a monolayer with a net sticking probability to ssaturation of ? 10?3. Oxygen adsorption reconstructed the (5 × 20) surface, and several ordered LEED patterns were observed. Upon heating, oxygen desorbed from the surface in two peaks at 676 and 709 K; the lower temperature peak exhibited atrractive lateral interactions evidenced by autocatalytic desorption kinetics. Hydrogen was also found to reconstruct the (5 × 20) surface to the (1 × 1) structure, provided adsorption was performed at 200 K. For all three species, CO, O2, and H2, the surface returned to the (5 × 20) structure only after the adsorbates were completely desorbed from the surface. |
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