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Croatica Chemica Acta, Vol.80 No.3-4 November 2007. -

The kinetics of homogeneous and heterogeneous nucleation processes of metal Ag, Pd nanoparticles

was studied by UV-VIS spectrometry. Silver nanoparticles were prepared in aqueous

solution by homogeneous nucleation using polyvinylpyrrolidone PVP and sodium citrate as

sterical stabilizers. Reduction was ensured by adding hydroquinone. According to kinetic functions,

reduction is an autocatalytic process: a slow, continuous nucleation is followed by a fast,

autocatalytic growth. The presence of polymer inhibits nucleation and retards the rate of particle

growth. Formation of palladium nanoparticles was investigated in aqueous medium via reduction

by hydrazine, using PVP and the clay mineral hectorite as stabilizers. Effects of the

polymer and concentration of silicate and palladium ions on the particle formation rate were

analyzed. The rate of reduction is decreased by increasing amounts of stabilizing agents and increased

by increasing concentrations of precursor ions. The kinetics of heterogeneous nucleation

was determined based on the adsorption of the palladium species at the clay mineral particles

and the viscosity of the hectorite dispersion.

palladium; silver; nanoparticle formation; UV-VIS spectroscopy; TEM



Autor: Szilvia Papp - ; Nanostructured Materials Research Group of the Hungarian Academy of Sciences, Szeged, Hungary Rita Patakfalvi -

Fuente: http://hrcak.srce.hr/



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