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

Abstract

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 AE 2 and 168 AE 2 , respectively. This indicates excellent surface super-hydrophobic properties, which originate from the uniqueness of their surface structures.

Layered Double Hydroxides as Catalytic Materials: Recent Development

“…The precursor route for a Co-based catalyst enables scalable preparation of CNTs at low cost. More lately, the supported Co/Al-LDH has been used as precursor for growth of novel carbon nanostructures [58]. Three types of carbon nanostructures (tubes, caterpillar-like fibers and interwoven spheres) were grown onto silicon-supported catalyst from a Co/Al-LDH precursor.…”

Synthesis of Novel Submicrometer‐Scale Flat Carbon Fibers and Application in the Electrooxidation of Methanol

“…The above result indicates that partial divalent Ni species in an LDH precursor can be reduced into metallic Ni in the present system, despite the presence of the difficultly reduced NiAl 2 O 4 spinel phase. Correspondingly, the incomplete reduction of Ni species favors the formation of small metallic Ni nanoparticles, originating from the ordered prearrangement of metal cations in the layers of an LDH precursor at an atomic level [25]. Fig.…”

“…Among them, the type and character of the utilized catalyst is the most important factor in the formation of CNFs with regular shapes and unique structures. Recently, we have found that CNTs and CNFs could be synthesized by catalytic chemical vapor deposition of acetylene over highly active cobalt-based supported catalysts derived from Co 2+ -containing layered double hydroxides (LDHs) [25]. It is well known that 2 O, consist of positively charged layers and negative anions in the interlayer [26], and the structural versatility of LDHs can be achieved by varying divalent or trivalent metal cations in the layers and the anions intercalated into the interlamellar galleries [27][28][29].…”

Large-scale Synthesis of Nitrogen-doped Carbon Nanotubes by Chemical Vapor Deposition Using a Co-based Catalyst from Layered Double Hydroxides

“…Various LDHs can be obtained by changing the proportion and variety of the divalent and trivalent cations and the interlayer anion. Recently, some research has indicated that LDHs can be used as catalysts after a controlled thermal treatment to prepare CNTs by CVD [20,21]. During the treatment LDHs lose their layered structure partly because of the evaporation of water molecules and form spinel metal oxides, like CoAl 2 O 4 and/or Co 3 O 4 , with high thermal stability and a high dispersion of metal cations.…”