Estudio DFT de la adsorción de átomos y dímeros de Cu, Ag y Au sobre SiO2

R.M. FERULLO , G.R. GARDA, P.G. BELELLI, M.M. BRANDA Y N.J. CASTELLANI

Isla Margarita, Venezuela

Congreso; XXXI Congreso Internacional de Químicos Teóricos de Expresión Latina; 2005

In this work, the adsorption of Mn (M: Cu, Ag, Au; nZ1–3) particles on the hSi–O$ defect of a SiO2 surface is studied in the framework of density functional theory. A charge transfer from the metal particle to the support is observed following the sequence: CuzAgOAu. This is in agreement with the greater ionization potential of the latter metal. The M1–MnK1OSih and Mn–OSih interactions of nucleation and adhesion processes, respectively, were analyzed from an energetic point of view. The strongest interaction is obtained always between two open-shell systems. When the comparison is performed among the metals, the bond strength of the M–M interaction follows the order: CuzAuOAg. The deep position of Ag d-levels in the energy scale could explain the relatively weak Ag–Ag interaction. If the M–oxide interaction is considered, this order in the bond strength was observed: CuOAgOAu. The strong adhesion for Cu could be ascribed to the greater charge transfer to the support and to a strong Cu(d)–O(p) interaction. On the other hand, for Au the charge transfer to the support is relatively small, while for Ag the Ag(d)– O(p) interaction is relatively weak due to the more localized Ag(d) band.n (M: Cu, Ag, Au; nZ1–3) particles on the hSi–O$ defect of a SiO2 surface is studied in the framework of density functional theory. A charge transfer from the metal particle to the support is observed following the sequence: CuzAgOAu. This is in agreement with the greater ionization potential of the latter metal. The M1–MnK1OSih and Mn–OSih interactions of nucleation and adhesion processes, respectively, were analyzed from an energetic point of view. The strongest interaction is obtained always between two open-shell systems. When the comparison is performed among the metals, the bond strength of the M–M interaction follows the order: CuzAuOAg. The deep position of Ag d-levels in the energy scale could explain the relatively weak Ag–Ag interaction. If the M–oxide interaction is considered, this order in the bond strength was observed: CuOAgOAu. The strong adhesion for Cu could be ascribed to the greater charge transfer to the support and to a strong Cu(d)–O(p) interaction. On the other hand, for Au the charge transfer to the support is relatively small, while for Ag the Ag(d)– O(p) interaction is relatively weak due to the more localized Ag(d) band.