Electronics, local structure and morphology of heterogeneous nanoparticles investigated by XAFS and SAXS techniques

LISANDRO J. GIOVANETTI; JOSE MARTIN RAMALLO LOPEZ; SHEVCHENKO, ELENA; ALDO F. CRAIEVICH; FÉLIX GREGORIO REQUEJO

Campinas

Workshop; 20a Reunion Annual de Usuarios del LNLS; 2010

Laboratorio Nacional de Luz Sincrotron

Nanoparticles (NP) with heterogeneous structures like core@shell, that comprise a core of one material and a coating shell of another material, or dumbbell-shaped NP (where one NP is linked to another) are of great interest because of their different possibilities to control their physicochemical properties. Since the size and material properties in dumbbell NP can be manipulated at will, a vast range of particles can be made with myriad properties, useful in areas like catalysis, nano-sensors for cellular imaging, gap controlled semiconductor, etc [1-4]. In this work we present a combined study using Transmission Electron Microscopy (TEM), Small Angle X-ray Scattering (SAXS) and X-Ray absorption spectroscopy (XAS) of Pt3Co and Pt3Co/Au dumbbell-shaped NP. The synthesis of dumbbell-shaped NP containing Pt3Co and Au NP involves two steps: (i) synthesis of Pt3Co NPs and (ii) deposition of gold onto one of facets of Pt3Co NP [5]. TEM and SAXS experiments were done on the dumbbell system and the isolated NP. By modeling of the obtained experimental SAXS curves it was possible to elucidate the morphology of the isolated NP and the structural modification introduced during the formation of the dumbbell structure. By the analysis of XAFS spectra obtained in Co-K, Au-L3 and Pt-L3 edges, changes in the electronic structure introduced by the stinking of the NP were analyzed. Acknowledgements: This work was partially supported by projects PIP 03079 (CONICET, Argentina), CIAM Argentine-Brazil-Canada collaborative project (CONICET-CNPq-NSERC), PICT 00038 and PICT 25515 (ANPCyT, Argentina) and D04B - XAS 6609/07 (LNLS, Brazil). [1]Shi WL, Zeng H, Sahoo Y, Ohulchanskyy TY, Ding Y, Wang ZL, Swihart M, Prasad PN. Nano Lett. 2006;6:875?881. [2]Yu H, Chen M, Rice PM, Wang SX, White RL, Sun SH. Nano Lett. 2005;5:379?382. [3]Daniel, M.-C. , Astruc, D. Chemical Reviews 104, (1), 2004, 293-346. [4]Burda, C., Chen, X., Narayanan, R., El-Sayed, M.A. Chemical Reviews 105, (4), 2005, 1025-1102. [5]Pellegrino, T., A. Fiore, et al. Journal of the American Chemical Society 128(20), 2006, 6690-6698.