Carbide-derived nanoporous carbon and novel core-shell nanowires

Carbide-derived carbon (CDC) nanowires (NWs) have been synthesized by the high-temperature treatment of small-diameter beta-SiC whiskers with Cl-2/H-2. A variety of physical measurements indicate that Si was extracted by exposure to Cl, and that the C in the carbon nanowires is primarily sp(2)-bonded. From BET measurements, the specific surface area of these carbon nanowires is 1.3 x 10(3) m(2)/g and they contain a network of nanopores. Nanoindentation measurements indicate that the SiC-derived C is not a stiff material, the elastic modulus being 5.0 +/- 1.2 GPa. High-temperature treatment of the CDC nanowires under an inert gas significantly increases the degree of graphitization. In addition, partial extraction was used to obtain core-shell structures having a thin and also very high surface area CDC shell; further treatment at high temperature was used to produce graphitized carbon shell-crystalline SiC core NWs.