Synthesis and characterization of TiO2@C core-shell nanowires and nanowalls via chemical vapor deposition for potential large-scale production

TiO2 nanowires and nanowalls core structures covered with carbon shell were selectively synthesized by a simple chemical vapor deposition (CVD) method using commercial titanium powder as the starting material. Morphology and structure of the products were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The core shell structure is composed of single crystalline rutile titanium dioxide wrapped by amorphous carbon shell. By adjusting the growth temperature, morphology of the products can be controlled from one-dimensional nanowires to two-dimensional nanowalls. While TiO2@C nanowires were a preferred structure at higher temperature, TiO2@C nanowalls dominated the final product at lower temperature. A growth mechanism was proposed based on the initial growth state of these nanostructures, in which solid-state diffusion of the elements involved in the reaction was assumed to play an essential role. The obtained TiO2@C core shell structures may find potential applications in various nanoscale realms such as optoelectronic, electronic and electrochemical nanodevices and the simple synthesis procedure promises large scale production and commercialization of the titanium oxide@carbon nanostructures. (C) 2011 Elsevier Inc. All rights reserved.