1Laboratoire d'Analyse Industrielle et Génie des Matériaux, Département de Chimie Industrielle, Faculté des Sciences et de l'Ingénierie, Université 08 Mai 1945 de Guelma, B.P. 401, Guelma 24000, Algérie.
2Département de Physique, Faculté des Sciences et de l'Ingénierie, Université 08 Mai 1945, Guelma, B.P. 401, Guelma 24000, Algérie.
3Groupe de Matériaux Inorganiques, Institut de Physique et de Chimie des, Matériaux de Strasbourg, UMR 7504 CNRS-ULP, 23 rue de Loess, 67037 Strasbourg cedex2, France.
Highly dispersed palladium nanoparticles have been obtained by ultrasonic irradiation of Pd(NO3)2 solution in presence of ethylene glycol (EG) and polyvinylpyrrolidone (PVP) at different sonication time.
The sonochemical reduction process of palladium ions (Pd(II)) to palladium atoms (Pd(0)) can be explained by the acoustic cavitation: formation, growth and collapse of bubbles. In the sonochemical process, there are three different stages where the reduction of Pd(II) ions in the aqueous solution can occur. The water pyrolyze into •H and •OH, the radical formation from EG, and the reduction of Pd(II) ions.
The UV-Visible results analyses show that the sonochemical reduction rate of Pd(II) into Pd(0), which control the palladium nanoparticles formation, depends on the sonication time. The reduction process can be divided in three periods. During the first sonication period, the Pd(II) ions are rapidly reduced into Pd(0) atoms and the formation of primary particles can occurs. The increase of sonication time, induces the progressive decrease of the Pd(II) reduction rate which enhance the growth of primary particles. The third period corresponds to the high sonication time, the reduction rate of Pd(II) ions is very weak and the growth of the stable PVP-Pd nanoparticles is negligible.
TEM and EDX investigations prove that the obtained suspension is constituted by the single palladium particles. These Pd nanoparticles are highly dispersed, with a rounded shape and an average diameter of about 4 nm.
Palladium nanoparticles, Kinetics, UV-Visible spectroscopy, MET, EDX
