Novel carbon nanostructures of caterpillar-like fibers and interwoven spheres with excellent surface super-hydrophobicity produced by chemical vapor deposition

The controlled growth of three types of carbon nanostructures (tubes, caterpillar-like fibers and interwoven spheres) was successfully achieved via the catalytic chemical vapor deposition of acetylene, using an effective, silicon supported catalyst derived from a Co-Al layered double hydroxide precursor. The materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy. The results show that the grown carbon nanostructures can be tuned by adjusting the duration of catalytic growth. Short growth duration of 20 min produces uniform carbon nanotubes, while long growth durations of 40 and 60 min result in the formation of caterpillar-like fibers and interwoven spheres, respectively. The growth mechanism of these structures is discussed on the basis of an overgrowth of the initially formed tubular carbon nanostructures. Furthermore, the morphology of the obtained carbon nanostructures has considerable effect on their wettability. Particularly, the as-grown caterpillar-like carbon fibers and interwoven spheres over the surface of the substrate exhibit rather high water contact angles of 163 +/- 2 deg and 168 +/- 2 deg , respectively. This indicates excellent surface super-hydrophobic properties, which originate from the uniqueness of their surface structures.