One-step in situ synthesis and characterization of W_(18)O_(49)@carbon coaxial nanocables

摘要

We demonstrate here in situ synthesis of bulk yield W_(18)O_(49)@carbon coaxial nanocables based on an easily controlled chemical vapor deposition process at relatively low temperature (760℃) using metallic tungsten powder and ethylene (C_2H_4) as the raw materials. Transmission electron microscope (TEM), energy dispersive x-ray (EDX), and x-ray diffraction (XRD) analyses indicate that the resultant nanostructures are composed of single-crystalline W_(18)O_(49) nanowires, coaxially covered with amorphous carbon walls. A vapor-solid (VS) mechanism is proposed to interpret the formation of the nanocables. The effect of carbon sources on the nanocable growth was investigated. The results revealed that the introduction of carbon species not only causes the production of W_(19)O_(49)@C nanocable structures, but also obviously modulates growth behaviors and core/shell diameter ratio of the nanocables. The obtained nanocables may find great applications in catalyst systems and optical and electronic nanodevices because of their enhanced surface properties and in high chemical stabilities.