Experimentally, Pt4Ge and Pt7Ge2 showed similar effects of Ge addition on CO TPD, i.e., the high temperature CO binding site was highly stable in repeated TPD runs, and we also observed diminished effects of adding carbon to both size PtGe clusters on the availability and strength of CO binding sites, suggesting that mechanisms are similar to those in Pt7Ge2. Fig. shows calculated structures and binding energies for CO adsorbed at different sites on Pt4Ge/alumina and Pt4GeC2/alumina, showing that CO binding remains strong after the addition of two C atoms. However, the binding strength is strongly affected by proximity to the Ge atom. The binding energies to Pt atoms that are directly bound to Ge are in the 1.14 eV to 1.58 eV range, but for Pt atoms distal to Ge, the CO binding energies are >2.5