Nuclation and Growth of Silver Nanoiparticles

R. MOIRAGHI, M. A. PÉREZ*, E. A. CORONADO AND V. A. MACAGNO

Bahía Blanca, Buenos Aires, Argentina

Simposio; III Encuentro de Física y Química de Superficies; 2007

The control of shape and size is the key to taylor physical and chemical properties of nanoparticles (NP’s) and nanostructures [1]. The study of the reaction mechanisms of the formation of NP’s is a relative unexplored field [2]. The one-pot synthesis is a scheme frequently used to obtain of NP’s, however only for the case of the hot-injection method such approach has been proved to produce monodisperse colloids in reproducible manner [3]. In such method, the programmed temperature changes of a reactive solution of the organometallic precursors in a coordinating solvent of low polarity allow the control over size/shape of NP’s, by driving nucleation and growth in separated timeframes. In aqueous systems, the mixing of the ions and complexes metallic precursors and the reducing agents in the one-pot scheme becomes a critical factor to control NP’s morphology [4]. With exception of the very early stages of nucleation where the reduction of metallic precursors can be considered a homogeneous reaction, the NP’s growth takes place at the nuclei surface whether their nuclearity is either below or over the critical nuclei value. This mechanism is also known as autocatalitic surface growth [5]. In the present communication, we discuss the mechanisms of NP’s growth obtained with the experimental model reaction between the silver ion (I) and the hydroquinone on the basis of UV-Vis spectroscopy, transimission electronic microscopy (TEM) morphological characterization and electrodynamics calculations. Using a one-pot scheme, the influence on the final NP’s morphology of different synthetic factors, like nature of the metallic precursor, reducing agent concentration, pH and stabilization agents, as well as of different conditions for the mixing of reactants are analyzed. [1] Ozin, G.A., Arsenault, A.C., Nanochemistry: A Chemical Approach to Nanomaterials, RSC Publishing, Cambridge, U. K. 2005. [2] M. A. Pérez,"Growth Mechanisms of Metal Nanoparticles” in Recent advances in Nanoscience, M. M. Mariscal and S. A. Dassie Eds., Research Signpost, 37/661 (2), Fort P.O., Trivandrum-695 023, Kerala, India (Aceptado 2007). [3] Mello Donegá, C., Liljeroth, P., Vanmaekelbergh, D.; Small 2005, 1, 1152. [4] Pérez, M. A.; Moiraghi, R.; Coronado, E. A.; Macagno, V. A.; J. Phys. Chem. C (submitted 2007). [5] Finke, R. G., “Transition-Metal Nanoclusters: Solution-Phase Synthesis, Then Characterization and Mechanism of Formation, of Polyoxoanion- and Tetrabutylammonium-Stabilized Nanoclusters” in Metal Nanoparticles- Synthesis, Characterization and Applications, Feldheim, D. L. and Foss, C. A. Eds., Marcel Dekker Inc., New York, USA, 2002.