Photochemical Preparation of Silver NanoparticlesSupported on Zeolite Crystals.

A facile and rapid photochemicalmethod for preparing supportedsilver nanoparticles (Ag-NPs) in a suspension of faujasite type (FAU)zeolite nanocrystals is described. Silver cations are introduced byion exchange into the zeolite and subsequently irradiated with a Xe–Hglamp (200 W) in the presence of a photoactive reducing agent (2-hydroxy-2-methylpropiophenone).UV–vis characterization indicates that irradiation time andintensity (I0) influence significantlythe amount of silver cations reduced. The full reduction of silvercations takes place after 60 s of a polychromatic irradiation, anda plasmon band of Ag-NPs appears at 380 nm. Transmission electronmicroscopy combined with theoretical calculation of the plasmon absorbanceband using Mie theory shows that the Ag-NPs, stabilized in the microporesand on the external surface of the FAU zeolite nanocrystals, havean almost spheroidal shape with diameters of 0.75 and 1.12 nm, respectively.Ag-NPs, with a homogeneous distribution of size and morphology, embeddedin a suspension of FAU zeolites are very stable (∼8 months),even without stabilizers or capping agents. [ABSTRACT FROM AUTHOR]