ISS CO Adsorption In Situ

Note that the peak corresponding to the Pt atoms and Zr basically represents the Zr atoms, since the platinum content is only 1 %. Thus, a lower ratio between the intensities of the peaks of O and Zr + Pt (ratio lo/lcpt+zr)) after reduction indicates an increase in Zr population at the surface. The decrease is higher after reduction at 500 °C, due to the higher degree of reduction of zirconia at this temperature. 

The CO adsorption at room temperature on the reduced sample at 300 C, (Fig. 11.12a) does not show significant changes, which suggests no interaction of CO with zirconia. However, adsorption of CO on the reduced sample at 500 °C (Fig. 11.12b) indicates that there are exposed zirconium cations on the surface interacting strongly with CO, thus causing a decrease in the intensity of Zr + Pt peak and consequently increasing ratio Io/I(pt+zr)) intensity [18-34]. Additional references related to this subject [91-107]. 

Wagner C, Riggs W, Davis L, Moulder J, Muilenberg G. Handbook of X-ray photoelectron spectroscopy. Eden Prairie, MN Perkin Ebner, 1979. 

Meijers ACQM, de Jong AM, Van Gruijthuijsen LMP, Niemantsverdriet JW. Preparation of zirconium oxide on silica and characterization by X-ray photoelectron spectroscopy, secondary ion mass spectrometry, temperature programmed oxidation and infra-red spectroscopy. Appl Catal. 1991 70 53-71. 

Morant C, Sanz JM, Galan L, Soriano L, Rueda F. An XPS study of the interaction of oxygen with zirconium. Surf Sci. 1989 218 331-45. 

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