The impact of FOs on the ordering of adsorbates on metallic surfaces definitely has an energetic background. As such, it should also be visible when performing catalytic reactions. Take as an example CO oxidation at platinum surface. In this case, the heat of CO adsorption systematically decreases with an increase in coverage up to 0.75 ML (MonoLayer) for both reconstructed hex and the unreconstructed (1×1) surfaces of Pt(100). Following this idea, Völkening and Wintterlin 66 were looking at CO oxidation on the Pt(111) surface with STM. They observed that initial islands of adsorbed oxygen atoms undergo rearrangement upon introduction of CO to the system. Their calculations indicate that the activation energy of the reaction rises proportionally to the number of neighboring O ad atoms. This observation alone hints at the presence of surface-mediated interactions, if one were to consider the inevitable repulsion between the atoms, similarly to the observations done in other works. Interestingly, the CO adsorbed in between the atoms of the (2×2)O ad domains was unable to desorb O ad and form CO2, contrary to the conclusion reached in an earlier kinetic study, where the weaker adsorption energy in such sites has been associated with higher reactivity. This results in a reaction happening only at the border of domains formed by adsorbed O ad and CO ad species. Again, such O ad behavior seems to be rooted in surfacemediated interactions via FOs.