Oxygen desorption from α-Al 2O 3 (0001) supported Rh, Pt and Pd particles

Abstract

Temperature-programmed desorption (TPD) was used to study the interaction of oxygen with both large (∼ 10 nm) and small (<2 nm) Rh, Pt and Pd particles supported on α-Al 2O 3(0001). The results of this study indicate that O 2 desorption from large particles of Rh, Pt and Pd is similar to that from low-index planes of the respective metal single crystals. Additionally, O 2 desorption from small Rh particles is similar to that from the close-packed planes of bulk Rh. In contrast, O 2 desorption from small particles of Pt and Pd occurs at a significantly higher temperature than that from the respective, low-index single crystal surfaces despite a much higher saturation oxygen coverage on the small particles. Possible explanations for the differences in O 2 desorption as a function of particle size for the various metals is discussed.