A rapid method for growth of metal nanoparticles on nanowire substrates A.D. LaLonde 1 , M.G. Norton 1, *, D. Zhang 2 , D. Gangadean 2 , A. Alkhateeb 2 , R. Padmanabhan 2 and D.N. McIlroy 2 1 School of Mechanical and Materials Engineering, Washington State University, Pullman, Washington, 99164-2920, USA; 2 Department of Physics, University of Idaho, Moscow, Idaho, 83844-0903, USA; *Author for correspondence (E-mail: norton@mme.wsu.edu) Received 13 April 2005; accepted in revised form 5 June 2005 Key words: nanoparticles, deposition, nickel, platinum, nanowires, chemical vapor deposition (CVD) Abstract The production of nickel and platinum nanoparticles on silica nanowire substrates using plasma-enhanced chemical vapor deposition has been investigated. Determination of particle size and particle size distri- bution was done using transmission electron microscopy (TEM). Ni nanoparticle diameters were found to be between 2 and 6 nm, with particle size increasing as the substrate temperature increased from 573 to 873 K. The size of Ni nanoparticles was found to be dependent on the chamber pressure during growth. The results indicate a competition between pressure-related diffusion within the vapor and dissociation of the precursor. Pt nanoparticle diameters were consistently found to be 2.5–3.0 nm at all deposition con- ditions. Insufficient thermal energy within the studied range results in a minimal contribution from surface diffusion, the primary mechanism for nanoparticle growth. Introduction The physical properties of metal nanoparticles (NPs) have been widely studied because of their potential for use in applications ranging from chemical sensors to lubricating oils. One of the most important areas for metal NPs is in catalysis because of their increased surface area compared to traditional thin film materials, which results in more reaction sites. Two metals that have been studied for this particular application are Ni and Pt (Che et al., 1999; Boudjahem et al., 2002; Bell, 2003; Wu & Chen, 2003; He et al., 2004; Mat- sumoto et al., 2004; Tang et al., 2004; Liu et al., 2005). Pt NPs have potential use in the oxidation of hydrocarbons, carbon monoxide (Bell, 2003), and methanol (He et al., 2004). Ni NPs are typically utilized in benzene hydrogenation (Boudjahem et al., 2002), ketone and aldehyde reduction (Mitchell, 2005), and the decomposition of hydra- zine (Wu & Chen, 2003). Controlling the particle size is necessary for many catalysts to enable large surface areas and to produce an optimal size for catalyzing a particular reaction. Another aspect in the use of NPs for catalysis is the substrate material used to support the metal. One common support used for catalytic materials is carbon black, which offers a large surface area (Matsumoto et al., 2004). However, a problem with carbon black is that the NPs can become trapped in deep cracks in the substrate, effectively making them inactive. Alternative support mate- rials such as carbon nanotubes (CNTs) and vari- ous ceramic nanowires (NWs) offer smooth surfaces and provide an optimal substrate for metal NPs. Journal of Nanoparticle Research (2006) 8: 99–104 Ó Springer 2006 DOI 10.1007/s11051-005-8385-6