Synthesis of carbon nanotubes in graphite microchannels in gas-flow and submerged-in-liquid reactors
Introduction
Carbon nanotubes (CNTs) [1], [2], [3] have been regarded as promising materials for various applications because many unique physical and chemical properties of CNTs have been recognized. Thus, there are numerous reports available concerning the applications in electronics [4], [5], [6], composite materials [7], [8], energy storage [9], [10], [11], sensor [12], [13], [14], and so forth. To utilize the superior features of CNTs for these applications, it is sometimes important to stabilize CNTs on specific locations. For such purpose, there are several ways for manipulation and localized growth of CNTs. For example in the CNT manipulation, ready-made CNTs can be conveyed to a localized position by dielectrophoresis [15], [12], [16], and these CNTs can be used as gas sensors [15]. For another example, the placement of catalysts for CNT-growth at targeted positions can enable ones to realize the localized growth of CNT on solid surfaces [17], [18], [19].
The growth of CNTs in microchannel is considered as one of the localized growth of CNTs. Recently, microfluidic reactors [20], [21], [22] have been receiving hot attention because many small particle products from this kind of reactor can exhibit uniform qualities, reportedly. Here, it should be noted that microfluidic reactor consists of microchannels whose widths are less than 1 mm. Thus, if CNTs can be synthesized on the surface of such microchannels, such CNTs inside the microfluidic reactor can be used as catalyst support when this microfluidic reactor is used for catalytic reaction. There are a few of literatures which report synthesis of CNTs inside the microchannel with support of plasma [23]. However, there is a drawback in such method when the channel is made of conductive materials so that it is difficult to keep plasma therein. In this study, graphite is used as a conductive material to fabricate microchannels, and two types of thermal reactors are examined to synthesize CNTs in microchannels.
Section snippets
Experimental
Before CNTs are synthesized in microchannels, the growth of CNTs on alumina plate surface is investigated. The alumina plate is convenient for visual observation of CNT-growth because the area where CNTs are produced becomes black on the white surface of alumina plate. From the contrast in color on the surface of this plate, one can easily distinguish between the area with well-grown CNT and that without CNT. In this experiment, CNTs are synthesized in a narrow space between two plates placed
CNT-growth in narrow space between paralleled plates by diffusion of carbon-source
When CNTs were synthesized on the alumina plate, the growth of CNTs can be visually observed. When CNT-growth is failed, the color of the plate surface should seem white that is the color of the bare alumina plate. On the other hand, the surface of the plate becomes dark when the CNT-growth is successful. The inter-plate spacing was changed by varying the diameter of the wires between the two plates as mentioned in Section 2.
To achieve the synthesis of CNTs, carbon-source gas must reach the
Conclusions
CNTs are synthesized on the surface of the graphite microchannels using GF-reactor and SIL-reactor. In GF-reactor, carbon-source gas is introduced through the microchannel by convective flow. In SIL-reactor, carbon-source gas is supposed to diffuse into the microchannel from liquid contacted with the microchannel. As a result, CNTs can be synthesized in both reactors although there is a significant distribution of CNT production. In GF-reactor, the distribution of CNTs should be ascribed to the
References (26)
- et al.
J. Cryst. Growth
(1976) - et al.
Carbon
(2004) - et al.
Diam. Relat. Mater.
(2008) Nature
(1991)- et al.
Nature
(1993) - et al.
Appl. Phys. Lett.
(2005) - et al.
Appl. Phys. Lett.
(2003) - et al.
Surf. Sci.
(2001) - et al.
Nat. Mater.
(2003) - et al.
Appl. Phys. Lett.
(1997)
Electrochem. Solid State Lett.
J. Phys. Chem. B
Science
Cited by (8)
Synthesis of carbon nanotubes by catalytic chemical vapour deposition: A review on carbon sources, catalysts and substrates
2016, Materials Science in Semiconductor ProcessingCitation Excerpt :It was also observed that the Ni–Mo catalyst produces mostly CNTs with different diameters where as Co–Mo catalysts gave largely amorphous carbon. Additionally, Shiroishi et al. [274] achieved the growth of CNTs on the soda lime glass at the low temperature less than 550 °C by the use of novel catalyst Fe–Zr–N without the etching gas and in 2010, Sano and his colleagues [275] evaluated two systems of carbon sources/metallic catalyst for CNTs growth (1) benzene/iron and (2) ethanol/cobalt and reported the effect of two different reactors (gas flow reactor and a submerged-in-liquid reactor) on the quality of CNTs. Recently in 2014, Kavita et al. [227] synthesized CNTs on Co catalysts supported on MgO (i.e Co/MgO) by CVD using waste plastic, ispropanol and ethanol as carbon source and reported that high degree CNTs can be grown from waste plastic with different operating parameters.
Carbon nanotubes: A novel material for multifaceted applications in human healthcare
2017, Chemical Society ReviewsCVD-synthesized carbon nanotubes
2016, Carbon Nanomaterials Sourcebook: Graphene, Fullerenes, Nanotubes, and NanodiamondsSynthesis, modification, and characterization of nanocarbon electrodes for determination of nucleic acids
2016, Handbook of Nanoelectrochemistry: Electrochemical Synthesis Methods, Properties, and Characterization TechniquesUpdate on CNT/polymer nano-composites: From theory to applications
2015, Analysis and Performance of Engineering Materials: Key Research and Development