An Au/SiO2 system with most of the metal particles less than 2.0 nm in size were prepared by deposition on silica of preformed gold sols derived from Au(PPh3)3Cl. In this form, it was inactive in the CO + O2 reaction at ca. 333 K, because of the presence of phosphine ligands on the surface of metal particles. The system became catalytically active in this reaction after treatment in O2 at 673 K, which also resulted in a slight sintering of the metal phase (mean size ) 2.9 nm). By subsequent heating in H2 at 673 K, the mean size of gold particles increased up to 3.4 nm. Such particles exhibited a lower amount of step surface sites able to adsorb CO, but became more active in the CO + O2 reaction. This suggested that the reaction steps involving oxygen can occur more effectively on Au sites present on larger and smoother gold particles.

Nanometer-sized gold particles supported on SiO2 by deposition of gold sols from Au(PPh3)Cl

BIELLA, SERENA;
2003

Abstract

An Au/SiO2 system with most of the metal particles less than 2.0 nm in size were prepared by deposition on silica of preformed gold sols derived from Au(PPh3)3Cl. In this form, it was inactive in the CO + O2 reaction at ca. 333 K, because of the presence of phosphine ligands on the surface of metal particles. The system became catalytically active in this reaction after treatment in O2 at 673 K, which also resulted in a slight sintering of the metal phase (mean size ) 2.9 nm). By subsequent heating in H2 at 673 K, the mean size of gold particles increased up to 3.4 nm. Such particles exhibited a lower amount of step surface sites able to adsorb CO, but became more active in the CO + O2 reaction. This suggested that the reaction steps involving oxygen can occur more effectively on Au sites present on larger and smoother gold particles.
File in questo prodotto:
File Dimensione Formato  
J. Phys. Chem. B 2003, 107, 5453-5459.pdf

Accesso riservato

: Altro materiale allegato
Dimensione 159.15 kB
Formato Adobe PDF
159.15 kB Adobe PDF   Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11311/515217
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact