Mechanistic insight into the CO oxidation reaction at pure, Nb-doped and Mo-doped medium size Pt clusters

Density Functional Theory (DFT) simulations have been performed to study the CO oxidation reaction on a pure Pt18 cluster, and on Nb- and Mo-doped NbPt17 and MoPt17 clusters. The results show that a specially stable conformation of the pure cluster causes a sizable reduction of CO adsorption energy. Substituting one Pt atom by Nb or Mo has noticeable effects, charge transfer to the surface Pt atoms and destabilization of the special Pt18 ground state conformation, which result in an enhacement of CO binding for the doped cluster. Finally, molecular oxygen binds strongly to pure and Nb- or Mo-doped clusters, and easily dissociates and reacts with co-adsorbed CO, with reaction barriers not exceeding 0.8 eV.