Charanjeet Singh

Production of controlled architectures of aligned carbon nanotubes by an injection chemical vapour deposition method

High purity, aligned multi-wall carbon nanotube films were grown on quartz substrates by injecting a solution of ferrocene in toluene into a suitable reaction furnace. The injection CVD method allows excellent control of the catalyst to carbon ratio. The detailed study presented here demonstrates how such a system can be used to control the nanotube diameter, length, alignment and yield by manipulating the experimental parameters. Primary growth was found to occur via a base growth mechanism, although overgrowths of single wall carbon nanotubes were obtained under certain conditions. Such a method also allows nanotubes of various packing densities to be produced which may be useful for specific applications such as electrodes.

Towards the production of large-scale aligned carbon nanotubes

A novel method is presented to produce high purity, aligned multi-walled carbon nanotube films grown on thin quartz flakes by injecting a solution of ferrocene in toluene. After reaction, these quartz flakes support arrays of nanotubes arranged perpendicular to the surfaces of the substrate. This method is seen to increase the yield of nanotubes dramatically compared to the conventional injection CVD method. Such a method may offer the possibility of producing aligned nanotubes at large scales. In addition, the analysis established the presence of bands of varying iron concentration within this type of material.

Production of aligned carbon nanotubes by the CVD injection method

High purity, aligned multi-walled carbon nanotubes films were grown on quartz substrates by injecting a solution of ferrocene in toluene. The injection CVD method allows excellent control of the catalyst to carbon ratio. The nanotube diameter, length and alignment were controlled by varying the reaction parameters. In particular, the effects of temperature, catalyst concentration and reaction time have been investigated.

Electrolytic, TEM and Raman studies on the production of carbon nanotubes in molten NaCl

Abstract The production of carbon nanotubes (CNTs) by the electrolysis of molten NaCl was investigated by examining the effect of electrolysis duration, current density and voltage. It was found that as the electrolysis was run for longer periods the cathode eroded, changing the current density and consequently preventing nanotube production. The electrolysis was also inhibited by the anode effect and the formation of a sodium layer on the top of the electrolyte. The cell was modified to avoid these difficulties and then optimised under voltage control. Minimum and optimum voltages and current densities were found for CNT production. However, it was discovered that the percentage of nanotube produce still fell as the electrolysis progressed despite minimising the variation in the current density. The nanomaterial produced was studied by TEM. In particular, it was observed that half of the nanotubes were coated with amorphous carbon, suggesting a two-stage growth process. No link, though, was established between the growth conditions and the morphology of the nanotubes. Raman spectroscopy showed that the quality of the nanotubes was comparable to those produced by the CVD route. Titration was used to establish the uptake of sodium into the cathodes, providing evidence for the intercalation growth mechanism.

Synthesis of high purity single-walled carbon nanotubes in high yield

A simple method for the synthesis of high purity single wall carbon nanotubes has been developed by using nickel formate as a precursor for the formation of nearly mono-dispersed nickel seed-nanoparticles as catalysts in the CVD growth process.