Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5426689 | Surface Science | 2006 | 8 Pages |
We have investigated the oxidation behavior of Pd nanoparticles grown epitaxially on MgO(1Â 0Â 0) single crystal substrates. We find that the interaction of oxygen with octahedral Pd nanoparticles at 500Â K can be subdivided in three stages: above 10â6Â mbar O2 pressure, the particles start to flatten; above 10â3Â mbar, the particles begin to shrink laterally and to be less truncated at the corners. The formation of epitaxial bulk PdO sets in at oxygen pressures above 0.1Â mbar, which is accompanied by a continuous shrinkage of the Pd particles. Our results point to a novel nanoparticle oxidation mechanism: the Pd particles act as dissociation centers for O2 and serve at the same time as source for Pd atoms resulting in epitaxial PdO growth on MgO(1Â 0Â 0).