Comparison of the Adsorption of Ni, Pd, and Pt on the (0001) Surface of α-Alumina

We compare the adsorption of Ni, Pd, and Pt on the Al-terminated (0001) surface of alpha-Al2O3 at 1/3 ML coverage using first principle methods. Although belonging to the same group in the periodic table, Ni has a different adsorption site from Pd and Pt: while Pd and Pt adsorb on the top of a surface oxygen atom, Ni adsorbs at a hollow site between three oxygen atoms. The difference can be due to the smaller atomic radius and the emptier d band of Ni leading to stronger interactions between the three 0 atoms beneath. Nevertheless, owing to electrostatic factors and different metal-aluminum binding characteristics, Ni has a lower binding energy to the surface than Pt, but higher than Pd.