Applied Catalysis A: General 260 (2004) 87–91 Behaviour of transition metals catalysts over laser-treated vanadium support surfaces in the decomposition of acetylene Jin Won Seo a , Klara Hernadi a,b,∗ , Csilla Mikó a , László Forró a a Institute of Physics of Complex Matter, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland b Department of Applied and Environmental Chemistry, University of Szeged, H-6720 Szeged, Rerrich B. tér 1, Hungary Received in revised form 30 September 2003; accepted 9 October 2003 Abstract Laser-treated vanadium plates having high surface area were used as catalyst support in carbon nanotube synthesis under catalytic vapour deposition (CVD) conditions. Catalytic activity of various transition metals such as Fe, Co, or Ni was compared in the decomposition of acetylene at 720 ◦ C. Transmission and scanning electron microscopy (SEM) observations showed that there were significant differences between carbon deposits formed over the various transition metal catalysts. Carbon nanotubes with the best quality were obtained over the iron catalyst. The density is high and carbon nanotubes of small diameter (10–15 nm) are typical in this sample. While the carbon source was mainly converted to amorphous or fibre-like material over cobalt and nickel catalysts, vanadia-supported iron provided carbon nanotubes of well-graphitized walls. © 2003 Elsevier B.V. All rights reserved. Keywords: Carbon nanotubes; Laser-treated vanadium; CVD 1. Introduction The discovery of fullerenes [1] and carbon nanotubes [2] in the mid-1980s and the early 1990s, respectively, di- rected researchers’ attention not only to carbon nanostruc- tures but also to the formation of other new inorganic ma- terial types. For the synthesis of carbon nanotubes several successful methods are known. Besides arc discharge and laser ablation [3–5] techniques, catalytic decomposition of carbon-containing compounds (catalytic vapour deposition, CVD), in the presence of a proper catalyst can provide carbon nanotubes with high selectivity [6–9]. In the latter method, the types of both metallic particles and catalyst sup- port, moreover, their interaction play significant role as far as activity is concerned. Various silica and alumina com- pounds and other oxides proved to be the most effective catalyst supports [10,11]. Supported transition metals such as iron, cobalt, nickel and their alloys showed outstanding activity in carbon nanotube formation [12–14]. Tubular structures of inorganic materials having presum- ably unique physical, electronic and mechanical properties can be synthesized by various methods. Carbon nanotubes ∗ Corresponding author. Tel.: +36-62-544-626; fax: +36-62-544-619. E-mail address: hernadi@chem.u-szeged.hu (K. Hernadi). may serve as template during the synthesis of tubules of different inorganics such as vanadium pentoxide [15], sil- icon dioxide [16], or others [17–19]. Tubular structure of extremely large surface area can also be generated by laser-assisted oxidation of vanadium [20–23]. The latter material has already been tested as support using cobalt catalyst under CVD conditions, and both carbon nanotubes and fibres were formed in the decomposition of acetylene [24]. As a catalyst having outstanding activity it is also widely used in various catalytic reactions [25–27]. Every new material of nanometer scale, specially tailored nanostructures has the potential of possible nanoelectronical or nanomechanical applications. Other metals than cobalt were found to be selective in carbon nanotube formation, moreover, outstanding activity of Ni–V alloy has been shown recently [28]. For a deeper understanding of the role of the catalyst particles and the support, in this work we contin- ued our investigation of vanadium-supported transition metal catalysts under CVD conditions. 2. Experimental In order to prepare high surface area catalyst support of vanadium pentoxide, metallic polished vanadium plates 0926-860X/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.apcata.2003.10.003