Interaction of NO with Au nanoparticles supported on (100) terraces and topological defects of MgO

The adsorption of nitric oxide (NO) on Aun (n = 1-3) particles deposited on anionic (O2−) sites of MgO has been studied using the DFT (Density Functional Theory) approach. The regular O2− sites of MgO(100) and the sites in edge and corner topological defects with high symmetry of MgO were considered. The adhesion energy of Aun to MgO is larger for Au2 and Au3 due to higher polarization effects. On the other hand, the interaction strength of NO with supported Aun particles depends mainly on the electronic configuration (open or closed shell) of the particle; the Au particles with odd number of atoms show larger NO binding energies. A comparison was performed with the reactivity of free Aun particles. From this, it is possible to conclude that the support enhances the NO-Aun bonding strength for the monomer, weakens this interaction in the case of the dimer, and does not have an effect in the trimers. Besides, the NO-Aun bonding is essentially insensitive to the coordination of the anionic site where the Aun particle is linked. A large red-shift of the N-O stretching frequency was obtained, particularly for the Au particles with odd number of atoms, due to a negative charge transfer from Au to NO.