Abstract
Silica microtube and carbon nanotube hybrid structures have been synthesized by catalytic chemical vapor deposition using either methane or ethene as the carbon source, and cobalt-grafted or impregnated silica tubes (200–800 nm) as catalyst. The cobalt-grafted catalyst shows a high resistance to reduction (>1000 °C) and selectivity to single-wall carbon nanotubes (SWCNT). While ethene deposition produces more carbonaceous material, methane experiments show higher selectivity for SWCNT. After removing the silica with an excess of HF, the carbon nanostructure endured, resulting in a coaxial carbon nanostructure. The novel hybrid nanostructures obtained consist of a submicron-sized tube, with walls that are formed by a succession of carbon/silica/carbon layers to which multiwall (20–25 nm) and/or single-wall (0.6–2.0 nm) carbon nanotubes are attached. This synthesis approach combines the mechanical properties of carbon nanotubes and the thermal properties of silica tubes into a synergetic nanostructured material, opening further possibilities for polymer reinforcement and potential applications in catalysis.
Highlights
There is ongoing interest, globally, in research topics related to the development of new nanomaterials with unknown properties
Carbon nanotubes have mainly been synthesized by three methods: laser ablation [5], catalytic chemical vapor deposition (CCVD), and arc discharge [6,7]
We investigate the formation of silica-carbon hybrid nanotubes using cobalt-doped silica tubes (200–800 nm) as the catalyst, on which carbon nanotubes are grown by means of CCVD
Summary
There is ongoing interest, globally, in research topics related to the development of new nanomaterials with unknown properties. One of the cheapest and simplest processes for obtaining the silica tubes is the one proposed by Nakamura and Matsui [23], in which in-situ formed DL-ammonium tartrate needle-like structures are used as templates [26]. Through this process, silica submicron tubes (0.8–1.0 μm) can be obtained alongside spherical silica particles as a byproduct. We investigate the formation of silica-carbon hybrid nanotubes using cobalt-doped silica tubes (200–800 nm) as the catalyst, on which carbon nanotubes are grown by means of CCVD with methane or ethene These tubular silica-carbon structures lead to the formation of a synergistic material [32] in a nanostructure likely to have good thermal, electrical, and mechanical properties
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