Nanoagregats de Nickel et d’Argent

Abstract

Metallic aggregates in colloidal phases or supported aggregates attract increasing attention of researchers because of the wide range of possible applications (catalysis, environment, non-linear optics, biology and medicine). Radiolysis ranks among the most effective methods for the reduction of ions, giving the possibility of synthesis of aggregates of atoms. It is a powerful method to control the size of the particles, their location on the surface or volume. In the first part of this work, the morphological and structural properties of silver aggregates supported on silica were studied. X-ray diffraction identified the Ag6Si2O7 phase for different Ag+ ion charges as well as heat-treated samples. The FTIR spectroscopy study of Ag/SiO2 samples revealed the vibrations of Si-O-Si, Si-OH, Ag-O and Ag-SO4 bonds at the respective wave numbers 468, 810, 615 and 641 cm-1. The study of the optical properties of Ag/SiO2 nanoagreggates by UV- visible spectrophotometry showed the presence, in addition to a broadband in the visible range, three peaks in the UV domain. After reduction under hydrogen, the metal Ag phase of nanometric size was identified by XRD. In the second part, we studied, by time-resolved pulse radiolysis, nickel clusters in suspension. The formation of Ni+ ions and then those of nickel atoms was observed. The ionizing radiation generation of nickel aggregates in solution was observed for the first time live during this work.