The higher adsorption energy on the middle layer site and on the interface site (i) site compared to the adsorption on the top layer sites is mainly attributed to coordination effects, which are reflected also in the up-shifted captured energies of the d-band center (see Table ). This effect is present also for adsorption on the interface (ii) site, but counteracted and compensated by the higher positive contribution from the deformation energy and change in interface energy.