Scientific Results

Physico-chemical properties of Pd nanoparticles produced by Pulsed Laser Ablation in different organic solvents

Year: 2012

Authors: Cristoforetti G., Pitzalis E., Spiniello R., Ishak R., Giammanco F., Muniz-Miranda M., Caporali S.

Autors Affiliation: National Institute of Optics, Research Area of National Research Council, Via G. Moruzzi 1, 56124 Pisa, Italy; Institute of Chemistry of OrganoMetallic Compounds, Research Area of National Research Council, Via G. Moruzzi 1, 56124 Pisa, Italy; Dept. of Chem. Eng. And Material Science, University of Pisa, Via Diotisalvi 2, 56126 Pisa, Italy: Dept. of Physics, University of Pisa, Largo B. Pontecorvo 3, 56127 Pisa, Italy; Dept. of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy

Abstract: Palladium nanoparticles are arousing an increasing interest because of their strong activity in heterogeneous catalysis in a wide range of reactions. Driven by the interest of producing Pd nanoparticles to be deposited for catalysis over hydrophobic supports, we investigated their synthesis via Pulsed Laser Ablation in Liquid in several organic solvents, as acetone, ethanol, 2-propanol, toluene, n-hexane. The colloids were produced by using a Nd:YAG ns laser and without the addition of surfactant agents. The morphology, composition, stability and oxidation state of the obtained nanoparticles were investigated by TEM-EDS analysis, UV-vis spectroscopy, X-ray Photoelectron Spectroscopy and micro-Raman spectroscopy. The results evidence that the nature of the solvent influences both the yield and the physico-chemical properties of the produced nanoparticles. While in acetone and alcohols spheroidal, non aggregated and stable particles are obtained, in case of toluene and n-hexane few unstable particles surrounded by a gel-like material are produced. Raman/XPS measurements suggest the presence of amorphous or graphitic carbon onto crystalline Pd nanoparticles, which could have hindered their growth and determined the observed smaller sizes if compared to nanoparticles produced in water. The stability of Pd colloids obtained in acetone and alcohols was attributed to adsorbed anions like enolates or alcoholates; non polar solvents like toluene and n-hexane, unable to give rise to adsorbed anionic species, cannot provide any stabilization to the palladium nanoparticles. XPS analyses also evidenced a partial oxidation of particles surface, with a ratio Pd2+: Pd-0 of 1:2.5 and 1:4 in acetone and ethanol, respectively. (C) 2011 Elsevier B. V. All rights reserved.

Journal/Review: APPLIED SURFACE SCIENCE

Volume: 258 (7)      Pages from: 3289  to: 3297

More Information: The authors gratefully thank the Italian Ministero dell\’Universita e Ricerca for the financial support. The work was supported by MIUR Grants PRIN 2008. F. Giammanco e and M. Muniz-Miranda wish to acknowledge funding from the project NABLA (Decree n.4508-September 1, 2010 by Regione Toscana-Italy, PAR FAS 2007-2013 funds, Action 1.1.a.3).
KeyWords: pulsed laser ablation in liquid; palladium nanoparticles; organic solvents; nanoparticles synthesis; enhanced Raman-scattering
DOI: 10.1016/j.apsusc.2011.11.084

Citations: 42
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