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Accueil > Séminaires > Archive des séminaires d’Utinam > 2015

Christos Argirusis

Sonoelectrochemistry - a versatile tool for the preparation of nanomaterials

jeudi 15 octobre 2015, 14h00

salle de conférences de l’observatoire

Christos Argirusis, Director of the Laboratory of Inorganic Materials Technology, Université Technique Nationale d’Athènes, Synthesis and Development of Industrial Processes Department

Résumé :

Sonochemistry is the research area in which molecules undergo a chemical reaction due to the application of powerful ultrasound radiation (20 kHz–10 MHz) [1] . The physical phenomenon responsible for the sonochemical process is acoustic cavitation. This theory of the hot spot mechanism claims that very high temperatures (5000–25,000 K) are obtained upon the collapse of the bubble and chemical bonds can be broken. Since this collapse occurs in less than a nanosecond [2,3], very high cooling rates, in excess of 1011 K/s, are also obtained. This high cooling rate hinders the organization and crystallization of the products. The temperature in the interface between bubble and liquid is lower (ca. 1900 °C) than inside the collapsing bubble, but higher than the temperature of the bulk (usually between room temperature and 80 °C).

Sonoelectrochemistry, the application of ultrasound in electrochemistry has become increasingly popular in the past decade, especially in the field of materials science because of its potential in the production of nanomaterials, metals, alloys and composites with different properties and superior quality, hardness, and homogeneity, but also in analytical chemistry and electroorganic synthesis [5,6,7]. Electrochemical experiments can be performed using the ultrasonic horn generating the ultrasound itself as the cathode, which is especially suitable for the production of nanopowders. The major effects of ultrasound in electrochemical reactions are the enhanced mass transport due to acoustic streaming, influence of cavitation on reaction mechanism and surface cleaning and erosion [8].

The electrochemical quartz crystal microbalance technique (EQCM) allows to determine mass changes at the surface of the working electrode, which is one of the Au-electrodes of a piezoelectric quartz resonator, with a very high sensitivity. Recently we demonstrated that this technique can be applied also in the presence of an ultrasonic field, and is therefore suitable to study (sono)-electrochemical reactions [9,10].

References :

[1] K.S. Suslick, S.-B. Choe, A.A. Cichowlas, M.W. Grinstaff, Nature 353 (1991) 414
[2] R. Hiller, S.J. Putterman, B.P. Barber, Phys. Rev. Lett. 69 (1992) 1182
[3] B.P. Barber, S.J. Putterman, Nature 352 (1991) 414
[4] K.S. Suslick, D.A. Hammerton, R.E. Cline, J. Am. Chem. Soc. 108 (1986) 5641
[5] R. G. Compton, J. C. Eklund, F. Marken, Electroanalysis 9 (1997) 509.
[6] D. J. Walton, Arkivoc (2002) 198
[7] J.-L. Delplancke, J. Dille, J. Reisse, et al., Chem. Mater. 12 (2000) 946.
[8] C. E. Banks, R. G. Compton, A. C. Fisher, I. E. Henley ; Phys. Chem. Chem. Phys. 6 (2004) 3147
[9] O. Schneider, S. Matić, Chr. Argirusis ; Electrochim. Acta, 53 (2008) 5485–5495
[10] Chr. Argirusis, S. Matić, O. Schneider ; phys. stat. sol. (a) 205, No. 10, 2400–2404 (2008)

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