Adsorption of O2 and NO on Pd nanocrystals supported on Al2O3/NiAl(1 1 0): overlayer and edge structures

Adsorbate-induced overlayers on nanosized metal clusters have been studied with atomic resolution for the first time. Using scanning tunneling microscopy on supported palladium nanocrystals it was found that oxygen forms a p(2×2) overlayer phase and nitric oxide a c(4×2) overlayer phase. Adsorption of oxygen has a prominent effect on the cluster edges. On the basis of density functional theory calculations the effect is assigned to an oxygen-induced edge reconstruction.