Monitoring the interaction of adsorbates on metal surfaces by surface site engineering: the case of ethoxy on Cu, Pd, Ag and Au regular and stepped surfaces.

The interaction of ethoxy with the (111), (100), (511) and (310) surfaces of Cu, Pd, Ag and Au has been studied by means of periodic density functional calculations with the main aim to investigate, in a systematic way, the effect of the coordination number of surface metal atoms directly interacting with the adsorbate on the adsorption properties. The geometry of the adsorbed molecule is only slightly affected by the type of surface but the adsorption energy may change up to 40% on going from the (111) surface with atoms with coordination number of 9 to the (310) one where the coordination number decreases to 6. Analysis of the work function of the different surfaces and of the charge density reveals that the enhancement of the interaction is not due to variations in the charge transfer. However, a well defined trend between the interaction energy and the coordination number is clearly observed which is interpreted in terms of the d-band center model. These results strongly suggest that it is possible to tune the interaction energy by surface engineering.