Silver nanoparticles obtained by laser ablation as the active component of Ag/SiO2 catalysts for CO oxidation

Composite systems comprising a macroporous SiO2 support and silver nanoparticles preliminarily prepared by laser ablation in various liquids were synthesized and studied. Investigation of the catalytic properties of the synthesized composite catalysts demonstrated that, irrespective of particle size, non-interacting metallic silver particles in SiO2 matrix are not active toward the low temperature oxidation of CO, their activity appearing only at temperatures above 300 A degrees C. A combination of X-ray photoelectron spectroscopy and transmission electron microscopy allowed revealing that the activation redox treatment (O-2-500 A degrees C/H-2-200 A degrees C) of such particles in macroporous SiO2 matrix leads to the structures resembling surface silver silicates AgSiOx, which are active in CO oxidation at temperatures above 200 A degrees C.