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

Abstract

Nitrogen-doped carbon nanotubes (N-CNTs) have been synthesized at 850 °C via a CVD deposition technique by use of three ferrocenyl derivative catalysts, i.e. para-CN,-CF 3 and-Cl substituted-phenyl rings. The synthesized catalysts have been characterized by NMR, IR, HR-MS and XRD. The XRD analysis of the para-CF 3 catalyst indicates that steric factors influence the X-ray structure of 1,1′-ferrocenylphenyldiacrylonitriles. Acetonitrile or pyridine was used as carbon and nitrogen sources to yield mixtures of N-CNTs and carbon spheres (CS). The N-CNTs obtained from the para-CF 3 catalysts, in pyridine, have the highest nitrogen-doping level, show a helical morphology and are less thermally stable compared with those synthesised by use of the para-CN and-Cl as catalyst. This suggests that fluorine heteroatoms enhance nitrogendoping in N-CNTs and formation of helical-N-CNTs (H-N-CNTs). The para-CF 3 and para-Cl catalysts in acetonitrile yielded iron-filled N-CNTs, indicating that halogens promote encapsulation of iron into the cavity of N-CNT. The use of acetonitrile, as carbon and nitrogen source, with the para-CN and-Cl as catalysts also yielded a mixture of N-CNTs and carbon nanofibres (CNFs), with less abundance of CNFs in the products obtained using para-Cl catalysts. However, para-CF 3 catalyst in acetonitrile gave N-CNTs as the only shaped carbon nanomaterials.

Nitrogen-doped reduced graphene oxide-polyaniline composite materials: hydrothermal treatment, characterisation and supercapacitive properties

“…The presence of C-N and CQN peaks after the urea hydrothermal treatment indicates Ndoping/N functionalities in the samples. As in the work of Ombaka et al, 43 the broadening of the peak at ca. 1600 cm À1 can also be interpreted to indicate that CQC and CQN (due to the introduction and incorporation of nitrogen in the carbon backbone) peaks overlap in this absorption region.…”

Fundamentals and scopes of doped carbon nanotubes towards energy and biosensing applications

“…Morphology and surfaces chemistry in case of using pyridine and p-halogenated substitute derivate was significantly changed and the structure looks helical. Halogenated catalysts in acetonitrile resulted in the activation of Fe incorporation inside N-CNTs and this lead to decrease in N-CNTs diameter d,as well as limited secondary products CNF quantities[114]. A novel approach was initiated for enhancing Fe based catalysts properties in Fischer-Tropsch synthesis[115].…”

Nitrogen inclusion in carbon nanotubes initiated by boron doping and chlorination: Their use as electrocatalysts for oxygen reduction reaction

“…In this study, nitrogen was used as a carrier gas during synthesis of B-CNTs via chlorination. Previous studies have shown that the nitrogen content in the N-doped CNTs can be increased by using halogen-containing catalysts as the substrate (Ombaka et al, 2016). In another study, nitrogen and oxygen content were found to increase after boron addition during the synthesis of boron-nitrogen-oxygen co-doped carbons via chlorination (Ha et al, 2021).…”