Heteroatom‐containing ferrocene derivatives as catalysts for MWCNTs and other shaped carbon nanomaterials

Abstract

The effects of heteroatom‐containing ferrocene catalysts on the materials produced from chemical vapour deposition (CVD) floating catalyst synthesis were investigated. Specifically, the influence of nitrogen‐ and oxygen‐containing ferrocenoyl imidazolide and (N‐phenylcarbamoyl)ferrocene, and sulfur‐ and oxygen‐containing S,S‐bis(ferrocenylmethyl)dithiocarbonate on the structural morphology and distribution of the products as well as properties such as the thermal stability and crystallinity were studied. In addition, the influence of reaction parameters such as catalyst concentration and temperature were also investigated. The nitrogen‐containing catalysts produced N‐doped multi‐walled carbon nanotubes (N‐MWCNTs), whereas the sulfur‐containing catalyst produced primarily nano‐ and microspheres. A concentration of 2.5 wt% ferrocenoyl imidazolide was shown to be optimal for the synthesis of MWCNTs at 850 °C, with very low metal iron residue, highest thermal stability and highest yield (95%). In general, bamboo compartment length for N‐doped MWCNTs increased with temperature. Crystallinity trends were shown to be independent of catalyst and catalyst concentration in all cases and only dependent on temperature. The average diameter for MWCNTs was shown to be dependent on temperature, choice of catalyst and catalyst concentration in all cases. Copyright © 2012 John Wiley & Sons, Ltd.

Effect of boron concentration on physicochemical properties of boron-doped carbon nanotubes

“…Formation of B-CNFs was found to increase as the wt.% of triphenylborane (boron source) was increased (Table 1). This could be due to the fact that, at higher boron concentration and the 900 C temperature used in this study, catalyst agglomeration is enhanced hence favouring the formation of other SCNMs rather than CNTs [30]. Under similar temperature conditions (900 C), we have previously reported the synthesis of nitrogen-doped CNTs (NCNTs) by use of toluene as the carbon source and a ferrocene derivative, (4-{[(pyridin-4-yl)methylidene]amino}phenyl) ferrocene, as a catalyst and also as a nitrogen source.…”

A facile approach towards increasing the nitrogen-content in nitrogen-doped carbon nanotubes via halogenated catalysts

“…N-CNTs were synthesized by using a chemical vapour deposition (CVD) technique as outlined by Ombaka et al [8] and Oosthuizen et al [57]. In brief, three ferrocenyldiacrylonitriles with substituted para-CF 3 , -CN or -Cl (Fig.…”

Pyrrolic nitrogen-doped carbon nanotubes: physicochemical properties, interactions with Pd and their role in the selective hydrogenation of nitrobenzophenone

“…N-CNTs were synthesized by use of a chemical vapour deposition (CVD) method similar to that reported by Oosthuizen et al 31 and Koch et al 32 Briey, the compound 3-ferrocenyl-2-(4cyanophenyl)-acrylonitrile that we previously synthesized and characterized (ESI S1 †), was used as a catalyst, and it was synthesized following the protocol outlined by Imrie et al 33 and Ombaka et al 34 Acetonitrile was used as a carbon and nitrogen source, while ethylbenzoate was used as a source of oxygen. The solution used to synthesize N-CNTs was prepared by dissolving 0.25 g of the catalyst in 9.75 g of acetonitrile to make a total of 10 g of solution (i.e.…”