Our results taken together suggest that there is a correlation between the cluster-support interaction strength and the cluster-CO interaction strength; the stronger the cluster binds to the 2D surface, the weaker it binds to CO. This is true for monometallic and bimetallic PtGe nanoclusters. In addition, Ge alloying has the ability to reduce the Pt-CO interaction, although it might block the active sites due to the Ge-surface repulsion. Within the 2D materials considered in this work, we show that this effect can be exploited to the point that the interaction with CO is not even favorable, as it is found in the case of Pt5Ge5/germanene.