This behavior is quite different to the trend in PdAg/Pd(111) surface alloys. First of all, the shifts are much less pronounced for PdAg/Pd(111), where the center of the d-band on the Pd surface atoms is rather similar for Pd1Ag8, Pd2Ag7 and Pd3Ag6 systems, at about -1.34 eV, upshifted from the value for Pd(111) of -1.53 eV. This leads to a maximum shift of the d-band center of about 0.2 eV, while for PtAg/Pt(111) it reaches up to 0.6 eV. Thus, Ag induced changes in the activity are expected to be much more pronounced for the PtAg/Pt(111) surface alloys than for PdAg/Pd(111), depending on the optimum adsorption strength and thus on the optimum position of the d-band center. Next, we also evaluated the changes in the LDOS on the Pt atom in a Pt1Ag8 surface alloy upon varying the number of Ag underlayers from 0 to 2 (see Figure ). The LDOS on a Ag atom in a Ag(111) surface is also included. Replacing the Pt subsurface layer by a Ag layer leads to a strong narrowing of the LDOS at the Pt atom at the surface, and the same effect is also observed for inserting 2 Ag layers. Such kind of narrowing can be understood as result of a weaker coupling of the Pt atom to the Ag subsurface layer as compared to the situation with no Ag layer underneath. Commonly, such effects are described as vertical ligand effects. Together with the narrowing of the LDOS the center of the d-band shifts from Comparing again with PdAg surface alloys, the effects are again much smaller for these latter surface alloys, similar to the much smaller shifts observed upon varying the Pt or Pd ensemble size. Introducing one or two Ag underlayers for PtAg surface alloys shifts the center of the d-band by 0.02 and 0.07 eV, respectively, towards the Fermi level, while for PdAg surface alloys these shifts were 0.20 and 0.27 eV, respectively. Therefore, we expect also less pronounced changes in the binding energy of adsorbates to the Pd atom in the PdAg alloys with increasing number of Ag underlayers as compared to PtAg surface alloys. Finally, using RPBE/PAW we found the same trends for the shifts of the d-band center, which are listed in Table in the Electronic Supplementary Information.