Theoretical study of oxygen adsorption energy on supported metal cluster using d-band center theory and HSAB concept

This study estimated the oxygen adsorption energy (Delta E-O (ads.)) for the supported precious metal (PM) clusters (Pt-3, Pd-3, Rh-3 or Au-3) on support oxides (TiO2, ZrO2, Al2O3, La2O3, BaO or K2O). The estimated Delta E-O (ads.) values depend on the PM types as well as the types of support oxides. This study tried to predict the Delta E-O (ads.)values by simple calculations. The d-band center theory could describe the Delta E-O (ads.) values for the PM3 cluster under a vacuum condition (PM3 cluster without support oxides), namely, the interactions between the PM3 clusters and O atom depended on the d-band center (epsilon(d)) values of the PM3 clusters. There was a difference between the Delta E-O (ads.) values for the supported PM3 clusters and the PM3 clusters under the vacuum condition. This study succeeded in describing the difference by the HSAB (Hard-Soft-Acid-Base) concept. Finally, this study proposed a simple equation to predict the Delta E-O (ads.) values for the supported PM clusters. The proposed equation was derived from physicochemical considerations of the d-band center theory and HSAB concept, moreover, the equation contains only one free (adjustable) parameter.