Growth of carbon nanotubes and microfibers over stainless steel mesh by cracking of methane L.Z. Gao a, ⁎ , L. Kiwi-Minsker b , A. Renken b a School of Mechanical Engineering M050, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia b École Polytechnique Fédérale de Lausanne, EPFL-LGRC, CH-1015 Lausane, Switzerland Received 16 July 2007; accepted in revised form 3 November 2007 Available online 12 November 2007 Abstract The La 2 NiO 4 film was synthesized on the 304 stainless steel (SS) mesh. The hydrogen reduction of La 2 NiO 4 generated homogeneous nano- catalyst particles (probably Ni/La 2 O 3 ) over which methane was cracked, producing carbon nanotubes/microfibers and hydrogen. The carbon nanotubes/microfibers were strongly bonded to the SS mesh. It was observed that the methane conversion always reached its maximum at the cracking temperature of 750 °C regardless of its concentration varying from 5% to 100%. The cracking of 5% methane diluted in nitrogen generated multiwalled carbon nanotubes while the cracking of 10–100% methane resulted in the formation of carbon solid microfibers together with globular carbon particles. Higher concentration of methane created thicker carbon fibers and a 30% concentration of methane resulted in the highest deposits of carbon on the mesh. After a compressed air blow and ultrasonic treatment, the carbon deposits were still strongly adhered to the mesh. As a result of the carbon tubes/fibers coverage, the specific surface area of the SS mesh was enhanced significantly from 0.03 m 2 /g to 21– 45 m 2 /g. XRD, HRTEM and Raman studies confirmed that the carbon products were of graphitic structure. Such advanced mesh material would have great application potential in industrial catalysis and other areas. © 2007 Elsevier B.V. All rights reserved. Keywords: Stainless steel; La 2 NiO 4 film; Methane cracking; Carbon fibers; Specific surface area 1. Introduction Compared with a conventional bed of catalyst pellets, catalysts made of metal wire mesh have many advantages including lower pressure drop, higher thermal conductivity, mechanical strength, electromagnetic shielding, uniform fluid flow, less stagnation zones and hot-spots [1,2]. Wire mesh catalysts of precious metals (such as Pt, Ru, Ag) have long been used in the production of nitric acid from ammonia and formaldehyde from methanol [3]. These mesh catalysts, however, have low specific surface areas and are highly expensive as they consist of homogeneous bulk metal wires. There have been attempts to utilize wire meshes made of cheap iron or stainless steel as support of active catalyst component. A number of cheap wire mesh reactors have been used in the field of pyrolysis [4,5], the coal/char gasification and combustion [6] and catalytic oxidation of 1,2-dichlorobenzene [7]. The surface area of metal mesh is too low, high surface area is one of the most important factors for catalyst support. To improve the surface area of metal mesh is a necessary but difficult task to achieve. Carbon nanofibers (CNFs) and nanotubes (CNTs) are important materials which can be applied in many areas such as electrodes, adsorbents, lubricants, hydrogen storage, catalyst support etc. Metal foils covered with CNFs or CNTs could provide a gas impermeable layer, of high value for cryogenic or liquid fuel (e.g. LNG) storage applications. CNFs or CNTs are usually synthesized on the powder catalysts and need further separation and purification. In many cases, the application requires re-dispersion and reattachment of CNTs or CNFs to a support structure. One approach is to use polymer binder [8]. However, such method occludes much of the carbon nanofiber or nanotube' surface area. On the other hand, the polymer bound carbon nano materials are unstable at high temperatures. If the CNFs or CNTs can directly grow on the metal substrate, the reattachment of CNTs will become unnecessary. It is particularly important to have the CNFs or CNTs anchored Available online at www.sciencedirect.com Surface & Coatings Technology 202 (2008) 3029 – 3042 www.elsevier.com/locate/surfcoat ⁎ Corresponding author. E-mail address: lizhen@mech.uwa.edu.au (L.Z. Gao). 0257-8972/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2007.11.006