16:00-17:00
Exploring the frontiers of nanoparticles (NPs) prepared in microemulsions:
from “onion-like” NPs to subnm metal clusters
Prof. M.Arturo Lopez-Quintela (Laboratory of Magnetism and Nanotechnology (NANOMAG). Research Technological Institute. University of Santiago de Compostela. E-15782 Santiago de Compostela, Spain. )
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The production of monodisperse NPs is nowadays one of the most important challenges in Nanotechnology. The microemulsion technique is a powerful method to prepare simple metallic and oxide NPs1, as well as, core-shell and “onion-like” NPs. Although microemulsions cannot be considered as real templates, they constitute an elegant technique, which can provide a very good control of the final particle size. The reason for that is the complex interplay mainly between three parameters, namely, surfactant film flexibility, reactant concentration and reactant exchange rate. By adequately choosing these three parameters one can get NPs with a homogeneous distribution of particle sizes.2
In the last years we have further developed the microemulsion technique until its frontier with atom-resolution for the synthesis of metallic clusters (“particles” formed by Natoms < 100 atoms)3,4,. This has promoted a new very promising and exciting research area because clusters combine the scientific with the application interest. A number of new fascinating properties seem to appear at these subnm scales. As an example, fluorescence5, catalysis6, magnetism7, and circular dicroism have been already reported.
In this talk we will describe the microemulsion synthesis procedure showing preliminary results about the stability, structure, and properties of some clusters produced by this method9. Applications of these “new” materials will be discussed.
1See e.g. Lopez-Quintela, MA; Rivas, J. J.Colloid Interface Sci. 1993, 158, 446; Ibid, Curr.Opnion Colloid Interface Sci. 1996, 1, 806; Lopez-Quintela, M.A., Rivas, J. Blanco, M.C. Tojo, C. In "Nanoscale Materials", Ed. by L.M. Liz Marzan and P.V. Kamat. Kluwer Academic Plenum Publ., 2003, Chapter 6, pp.135-155.
2See e.g. L?pez-Quintela, MA. Curr. Opin. Colloid Interface Sci., 2003, 8, 137.
3Lopez-Quintela, M.A.; Rivas, J. Procedure for the synthesis of atomic quantum clusters. Spanish patent application No.P200502041, 2005. PCT/ES2006/070121, 2006.
4Guillen-Villafuerte, O.; Garcia, G.; Anula, B.; Pastor, E.; Blanco, M.C.; Lopez-Quintela, M.A.; Hernandez-Creus, A.; Planes, G.A. Angew.Chem.Int.Ed. 2006, 45, 4266.
5See e.g. Zheng, J.; Zhang, C.; Dickson, R.M. Phys.Rev.Lett. 2004, 93, 77402.
6Zhang, J., Sasaki, K., Sutter, E., Adzic, R.R. Science 2007, 315, 220.
7Yamamoto, Y.; Miura, T.; Suzuki, M,; Kawamura, N.; Miyagawa, H.; Nakamura,T.; Kobayashi,K.; Teranishi,T.; Hori,H. Phys.Rev.Lett. 2004, 93, 116801.
8Schaaff, T.G.; Whetten, R.L. J.Phys.Chem.B 2000, 104, 2630.
9Ledo-Suarez A , Rivas J, Rodriguez-Abreu CF, Rodriguez MJ, Pastor E, Hernandez-Creus A, Oseroff SB, Lopez-Quintela MA. Angew.Chem.Int.Ed. 2007, 46, 8823.
