Catalysis Today 76 (2002) 3–10 Mechanical and chemical breaking of multiwalled carbon nanotubes Krisztián Niesz a , Andrea Siska b , István Vesselényi b , Klara Hernadi b,∗ , Dóra Méhn b , Gábor Galbács c , Zoltán Kónya b , Imre Kiricsi b a Laboratoire de R.M.N., Facultés Universitaires Notre-Dame de la Paix, 61 rue de Bruxelles, B-5000 Namur, Belgium b Department of Applied and Environmental Chemistry, University of Szeged, Rerrich Béla tér 1, H-6720 Szeged, Hungary c Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary Abstract Catalytically prepared multiwall carbon nanotubes (MWNTs) were cut and functionalised by mechanical and/or chemical methods. Products were characterised by transmission electron microscopy, infrared spectroscopy and BET method. It can be concluded that physical and chemical breaking procedures complete each other very well. With certain MWNT samples containing surface oxides preliminary investigations were done for testing them as catalyst support. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Carbon nanotubes; Mechanical and chemical breaking; Surface functional groups; Pt/carbon catalyst 1. Introduction In heterogeneous catalytic processes special effort was made to prevent coke formation in the reaction of hydrocarbons [1,2]. As concerns the morphology of these deposits, many interesting results have been published [3,4]. From the 1970s, carbon fibers have careened to various applications and were investi- gated expansively [5,6]. The discovery of carbon tubules of nanometer size induced wide-ranging re- search activity on their synthesis, characterisation and possible applications [7–9]. Increasing effort is also being spent on their modification. The first modification of nanotubes occurs right after their production during their purification. When oxidative treatment is applied for the removal of amorphous carbon several structural vacancies may form [10]. ∗ Corresponding author. Fax: +36-62-544-619. E-mail address: hernadi@chem.u-szeged.hu (K. Hernadi). Decapping the tubes makes the interior accessible for various molecules. This time partial destruction of the nanotube structure takes place at the end of the tubes [11]. In both cases mentioned, the struc- tural imperfections are closed by functional groups such as COOH, OH or C=O. However, their con- centration, which is hardly measurable even by spec- troscopic methods, is not sufficient for immediate practical utilisations, e.g., using them as polymer fillers [12]. In order to increase the number of active sites (open ends) one has to cut the tubes into pieces. This can be achieved both by chemical and physical methods. Single-wall fullerene nanotube ropes were cut into 100–300 nm lengths which formed a stable colloidal suspension in water with the help of sur- factants [13]. Also single-walled carbon nanotubes (SWNTs) were dissolved in organic solutions by derivatisation with thionychloride and octadecylamine and were characterised by near-infrared spectroscopy [14]. 0920-5861/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0920-5861(02)00205-5