title: Ultrasonic treatment of glassy carbon for nanoparticle preparation.
abstract: Glassy carbon particles (millimetric or micrometric sizes) dispersions in water were treated by ultrasound at 20kHz, either in a cylindrical reactor, or in a "Rosette" type reactor, for various time lengths ranging from 3h to 10h. Further separations sedimentation allowed obtaining few nanoparticles of glassy carbon in the supernatant (diameter <200nm). Thought the yield of nanoparticle increased together with the sonication time at high power, it tended to be nil after sonication in the cylindrical reactor. The sonication of glassy carbon micrometric particles in water using "Rosette" instead of cylindrical reactor, allowed preparing at highest yield (1-2wt%), stable suspensions of carbon nanoparticles, easily separated from the sedimented particles. Both sediment and supernatant separated by decantation of the sonicated dispersions were characterized by laser granulometry, scanning electron microscopy, X-ray microanalysis, and Raman and infrared spectroscopies. Their multiscale organization was investigated by transmission electron microscopy as a function of the sonication time. For sonication longer than 10h, these nanoparticles from supernatant (diameter <50nm) are aggregated. Their structures are more disordered than the sediment particles showing typical nanometer-sized aromatic layer arrangement of glassy carbon, with closed mesopores (diameter ∼3nm). Sonication time longer than 5h has induced not only a strong amorphization (subnanometric and disoriented aromatic layer) but also a loss of the mesoporous network nanostructure. These multi-scale organizational changes took place because of both cavitation and shocks between particles, mainly at the particle surface. The sonication in water has induced also chemical effects, leading to an increase in the oxygen content of the irradiated material together with the sonication time.
authors.affiliation: LCME/CISM, Université de Savoie Mont-Blanc, 73376 Le Bourget-du-Lac cedex, France; Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, 32610 Tronoh, Seri Iskandar, Perak, Malaysia. Electronic address: jm.leveque@petronas.com.my.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Levêque
authors.affiliation: LCME/CISM, Université de Savoie Mont-Blanc, 73376 Le Bourget-du-Lac cedex, France. Electronic address: Laurent.Duclaux@univ-smb.fr.
authors.forename: Laurent
authors.initials: L
authors.lastname: Duclaux
authors.affiliation: Laboratoire de Géologie de l'Ecole Normale Supérieure de Paris, UMR CNRS 8538, 24 rue Lhomond, 75231-Paris Cedex 5, France.
authors.forename: Jean-Noël
authors.initials: JN
authors.lastname: Rouzaud
authors.affiliation: LCME/CISM, Université de Savoie Mont-Blanc, 73376 Le Bourget-du-Lac cedex, France.
authors.forename: Laurence
authors.initials: L
authors.lastname: Reinert
authors.affiliation: Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Komatsu
authors.affiliation: Institut Jean Lamour, UMR7198, Université de lorraine, BP 70239, 54506 Vandoeuvre-les-Nancy, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Desforges
authors.affiliation: Manufacturing and Industrial Processes Research Division, Faculty of Engineering, Univ. of Nottingham Malaysia Campus, 43500 Semenyih, Selangor, Malaysia.
authors.forename: Sadia
authors.initials: S
authors.lastname: Afreen
authors.affiliation: Manufacturing and Industrial Processes Research Division, Faculty of Engineering, Univ. of Nottingham Malaysia Campus, 43500 Semenyih, Selangor, Malaysia.
authors.forename: Manickam
authors.initials: M
authors.lastname: Sivakumar
authors.affiliation: Department of Chemistry, Shiga University of Medical Science, 520-2192 Seta, Otsu, Shiga, Japan.
authors.forename: Takahide
authors.initials: T
authors.lastname: Kimura
keywords: Glassy carbon; Microscopy; Nanoparticle; Sonication; Structure