Estudio teórico de la oxida-ción de CO con O₂ usando ca-talizadores de Au-Pd y Au-Pt

In the current study were development calculations based on Density Functional Theory (DFT) with the B3PW91/LANL2DZ approach for optimizing both monometallic and bimetallic systems: Au₉, Au₈Pd, Au₈Pt, AuPd₈, AuPt₈, Pd₉ y Pt₉. Such materials were theoretically tested as catalyst for the oxidation of carbon monoxide (CO) and the most favorable system for its further adsorption was determined. The substitution of Pt and Pd by Au atoms in the nonamers generated a change in the tridimensional structure of the system. The global reactivity analysis showed that the most reactive cluster is Pt₉ followed by AuPt₈. On the other hand, the Fukui indexes identified the most susceptible sites for a nucleophilic attack of both clusters. The CO adsorption generated an oxidation cascade which liberated ∼4.5 eV, indicating that the reaction is highly exothermic and exergonic. Both AuPt8 and Pt9 showed the lowest values of activation energy in the determining step of the mechanism. In general, the substitution of a Pt (Pd) atom by an Au atom does not affect the reactivity of the nonamers and then it is inferred that the AuPd₈ cluster could be a promissory catalyst in the CO oxidation.