RESEARCH PAPER Flame volume synthesis of carbon-coated WO 3 nanoplatelets and nanorods Wilson Merchan-Merchan • Alexei V. Saveliev • Sergio Granados Sanmiguel • Moien Farmahini Farahani Received: 10 July 2011 / Accepted: 30 October 2012 / Published online: 17 November 2012 Ó Springer Science+Business Media Dordrecht 2012 Abstract This paper reports the flame synthesis of WO 3 /C organic/inorganic octagonal nanoplatelets and nanorods. A high-purity tungsten wire inserted into the oxygen-rich region of the flame was used as a material source. The growth of the formed nanostructures starts with the oxidation of the metal probe, and evaporation of the oxide layer which is followed by the transport of the tungsten oxide vapors from the oxygen-rich to the hydrocarbon-rich zone of the flame. In the oxygen-rich zone, tungsten oxide vapors are crystallized into well- defined single crystal octagonal nanoplatelets. The continuous vapor deposition leads to the nanoplatelet growth in a preferred direction resulting in elongated rod-like nanostructures. The tungsten oxide structures entering the hydrocarbon-rich zone of the flame are coated with carbon layers forming hybrid WO 3 /C nanomaterials. The ideal conditions for the rapid and direct formation of these novel nanostructures are attributed to the synergy of the strong thermal and chemical gradients present in the flame volume. The entire process takes only a few seconds. A proposed mechanism of the hybridization process of the WO 3 nanorods and nanoplatelets to WO 3 /C is described. Keywords WO 3 /C organic/inorganic nanostructures Á Hybrid nanomaterials Á Nanoplatelets Á Volumetric flame synthesis Á Nanorods Introduction Tungsten in its natural state is a hard and brittle material that possesses exceptional mechanical and thermal properties. Tungsten can be combined with other elements to yield new compounds with new mechanical and electronic properties. For instance, tungsten carbide (WC) a compound containing an equal ratio of W and C atoms results in one of the hardest carbides with Young’s modulus of approximately 550 GPa. Tungsten can also be intercalated with oxygen to form transition metal oxides (TMOs). W oxides are among the most studied TMO nanostructures due to their remarkable superconductive, photochromic, electrochromic, opto- chromic, and gaschromic properties (Pol et al. 2006; Santato et al. 2001; Li et al. 2003; Wang et al. 2005; Righettoni et al. 2010; Jelle and Hagen 1999; Park et al. 2002; Kuznetsov et al. 2011). Recent research efforts in nanotechnology have taken tungsten to a new level by forming hybrid nanocomposites based on W x O y /C. The ability to form 1D structures consisting of a metallic or Electronic supplementary material The online version of this article (doi:10.1007/s11051-012-1276-8) contains supplementary material, which is available to authorized users. W. Merchan-Merchan (&) Á S. G. Sanmiguel Á M. F. Farahani School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019, USA e-mail: wmerchan-merchan@ou.edu A. V. Saveliev Department of Mechanical & Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA 123 J Nanopart Res (2012) 14:1276 DOI 10.1007/s11051-012-1276-8