Later, Watanabe and Motoo introduced the so-called bifunctional mechanism, where on a bimetallic surface one reactant adsorbs on the one type of surface atoms and the other one on the other type of surface atoms. Specifically, for the electrocatalytic CO oxidation on PtRu alloy surfaces they proposed that the interaction of H2O with the surface leads to the formation of adsorbed OH on the Ru atoms, and CO is adsorbed on the Pt surface atoms . At that point, electronic modifications of the respective surface atoms were not considered. While because of the high oxophilicity of Ru this mechanism was intuitively convincing, later experimental and theoretic studies revealed that not only OH, but also CO is more strongly adsorbed on Ru surface atoms than on Pt atoms . The high catalytic activity of these surfaces, which was observed experimentally, could be explained in a picture where due to the high coverages of OHad and COad the latter would be forced on the Pt surface sites . Essentially, the bifunctional mechanism can be considered as a LH mechanism with two or more different surface sites. The connection between physical/chemical catalyst properties and catalytic activity of a catalyst was reported already at the beginning of the last century by Sabatier ,