We must emphasize that CO and CO 2 poisoning are completely suppressed in Pt 4 Ge 3 under the conditions studied in this work (see Figure ). CO coverage is negligible even at P CO > P O2 . Our results indicate that the bistable kinetics of CO oxidation disappears; a single regime of fast CO oxidation rate is obtained by controlling the promoter concentration. The three different pressure conditions show very similar behaviour. O 2 * and O* are always the only species found at steady-state. The O 2 * coverage changes in a pyramid-like fashion, showing the highest value at intermediate temperatures. At P O2 = P CO , O 2 * remains the main dominant species until 350 K, whereas at P O2 > P CO , O* coverage becomes larger in the whole temperature range due to greater availability for O 2 dissociation sites. We highlight that the Pt-Ge nanoalloy starts to show very similar BGs for CO and O 2 at this precise Ge concentration. Thus, both reactants will adsorb with similar probabilities, and according to the Sabatier principle, the conditions for CO oxidation will be optimal. The importance of the magnitude of the binding energies on the overall performance of the reaction kinetics has been underlined previously. In addition, Pt 4 Ge 3 shows much faster kinetics for the CO* + O* than CO* + O 2 * step. This means that at initial times the TOF CO2 will be small as there will only be present CO* and O 2 *. But once O 2 starts dissociating, CO* will react immediately with the newly formed O* to give CO 2 . O 2 * accumulation is not problematic since it can dissociate to O* or react with CO(g) via ER. It is also important to mention that CO 2 desorption becomes spontaneous with increasing temperature, which prevents CO 2 poisoning. Regarding the reaction rates, except at P O2 > P CO , the TOF CO2 is higher at low temperatures and slightly decreases monotonically with temperature, but always maintains at high value. Interestingly, the highest TOF CO2 is obtained at 100 K for P O2 = P CO and P CO > P O2 , which is at least one order of magnitude higher as compared to other compositions. Part of these results may be found somewhat counterintuitive. However, it should be kept in mind that in these simulations the system is not at thermodynamic equilibrium but at a dynamic steady-state, which depends on the gas in/out flow: one should be cautious to rely solely on equilibrium data to rationalize the behaviour of systems out of equilibrium.It should be noted that Pt 4 Ge 3 will also eventually get poisoned at higher CO pressures, but harsher conditions will be needed than for Pt 4 . Regarding the role of Ge, DFT results suggest that on the one hand, Ge induces ligand effects (electronic effects) on Pt and reduces the affinity to CO, avoiding the overbinding of CO over O 2 . Similar ligand effects were also observed by Molina et al. for Nb and Mo doping. The advantageous mixing between both elements guarantees that Ge hybridizes with most Pt sites in the nanoalloy. On the other hand, our theoretical findings suggest that Pt-Ge also acts as a bifunctional catalyst. The addition of Ge into the catalyst creates new active sites for a more efficient oxygen adsorption. The nanoalloys show a dual adsorption behavior where CO is preferentially adsorbed on Pt and O 2 on Ge avoiding the competition for the active sites. Such behavior is in line with other oxophilic promoters such as Ru, Mo or Sn. Although in many instances Pt-Ge ensembles are needed for O 2 * and O* bridge adsorption, the ligand effects provide a similar adsorption strength to CO. Again, the high mixing guarantees that CO* and O 2 * (or O*) sites are in proximity for a facile diffusion and reaction, maximizing the bifunctional effect. Importantly, the ligand and bifunctional effects depend on Ge content, i.e., Ge alloying offers a new degree of freedom to control the catalytic properties of bimetallic catalysts. Apparently, this concentration dependence is very reaction-specific. Our results suggest that Pt 4 Ge 3 composition has the most adequate reactivity for CO oxidation, in contrast to dehydrogenation reactions. The microkinetic simulations further confirm that Ge alloying alters the CO oxidation bistable kinetics. Ge leads to a CO poisoning-free regime and fast CO 2 production prevails, at least within the pressure ranges studied in this work. Besides, the microkinetic simulations reveal that in this regime the Pt-Ge clusters may exhibit a high oxidation state (high O* coverage). Although our microkinetic model does not distinguish between Pt and Ge sites, the information about the binding energies is included; and thus, this high oxidation state may be indicative of a bifunctional mechanism. We speculate that part of the catalyst may remain reduced to the metallic state with Pt-Ge alloy formation, and part may be oxidized to GeO x . Therefore, now there is available an independent oxygen reservoir resistant to CO poisoning, i.e., GeO x , which can react with CO on Pt metallic sites.