Theoretical study of the CO Oxidation with O-2 using Au-Pd and Au-Pt catalysts

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: Au-9, Au8Pd, Au8Pt, AuPd8, AuPt8, Pd-9 y Pt-9. 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 byAuPt(8). 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 similar to 4.5 eV, indicating that the reaction is highly exothermic and exergonic. Both AuPt(8 )and Pt-9 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.