In situ formation of noble metal nanoparticles on multiwalled carbon nanotubes and its implication in metal–nanotube interactions Manuela Scarselli a, * , Luca Camilli a , Paola Castrucci a , Francesca Nanni b , Silvano Del Gobbo a , Eric Gautron c , Serge Lefrant c , Maurizio De Crescenzi a a Dipartimento di Fisica, Universita ` di Roma Tor Vergata, 00133 Roma, Italy b INSTM-Unita ` di ricerca di Roma Tor Vergata-Dipartimento di Scienze e Tecnologie Chimiche, Universita ` di Roma Tor Vergata, 00133 Roma, Italy c Institut des Mate ´riaux Jean Rouxel, CNRS-UMR 6502, 44322 Nantes Cedex 3, France ARTICLE INFO Article history: Received 29 July 2011 Accepted 24 September 2011 Available online 1 October 2011 ABSTRACT A simple method to decorate multiwalled carbon nanotubes (MWCNTs) with Au, Ag and Cu nanoparticles is illustrated. The method consists in directly depositing the selected metals by thermal evaporation on the carbon nanotubes. Comparative measurements carried out on samples that differ in the quantity and type of the deposited metal, reveal that isolated discrete particles form on the nanotube outer wall for all three metals. The CNT-based composites have been investigated by scanning and transmission electron microscopy to determine the size, shape and distribution of the nanoparticles. The results indicate that the quantity of evaporated metal only affects the nanoparticle size and not the average particle density. Particle composition was determined by X-ray photoelectron spectroscopy study. The results are discussed in terms of metal nanoparticle–tube interac- tions, an important issue for the fundamental and practical applications of similar MWCNT based composites. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction It is now well established that carbon nanotubes (CNTs) have so remarkable electronic and structural properties that can be used as active building blocks for a large variety of nanoscale devices [1–3]. To really disclose the true technological poten- tial of CNTs in different areas of nanotechnology, they have been incorporated in a variety of composite materials with even more attractive properties and possible applications. Due to their large active surface area, good conductivity and thermal stability, a large variety of entities ranging from inor- ganic [4], polymers [5] and biomolecules [6] have been inter- faced with CNTs. In this research field, an interesting class of derivatives rises from the controlled deposition of metal, alloy, metal oxide and semiconductive compound nanoparti- cles (NPs) on the CNT surfaces [4,7–10]. These nanoparticle hybrid systems have emerged as new class of nanomaterial whose magnetic, electronic, optical and catalytic properties differ deeply from those of the bulk material mainly depend- ing on their size and shape [11]. Many different methods for the controlled deposition and immobilization of NP along the CNTs have been illustrated [4,7–10]. These can promote either covalent linking using or- ganic- or bio-molecules, or a noncovalent linking through electrostatic interactions, chemical reduction, electrodeposit- ion and p–p stacking [4,8]. These methods can be summarized 0008-6223/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbon.2011.09.048 * Corresponding author: Fax: +39 06 2023506. E-mail address: manuela.scarselli@roma2.infn.it (M. Scarselli). CARBON 50 (2012) 875 – 884 Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/carbon