Deposition of Cu, Ag and Au small particles on reduced SiO2

FERULLO, RICARDO MARIO; GARDA, GRACIELA RAQUEL; BELELLI, PATRICIA GABRIELA; BRANDA, MARÍA MARTA; CASTELLANI, NORBERTO JORGE

JOURNAL OF MOLECULAR STRUCTURE THEOCHEM

Elsevier

Año: 2006 vol. 769 p. 217 - 223

0166-1280

In this work the adsorption of Mn (M: Cu, Ag, Au; n = 1-3) particles on the ºSi-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: Cu » Ag > Au. This is in agreement with the greater ionization potential of the latter metal. The M1-Mn-1OSiº and Mn-OSiº 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: Cu » Au > Ag. 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: Cu > Ag > Au. 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.