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

Journal Article · Tue Mar 15 00:00:00 EDT 2016 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2016.01.007· OSTI ID:22577803

Ombaka, L. M. ^[1]; Ndungu, P. G. ^[1]; Omondi, B. ^[1]; McGettrick, J. D.; Davies, M. L. ^[2]

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1. School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000 (South Africa)
2. SPECIFIC, Swansea University, Baglan Bay Innovation Centre, Baglan, Port Talbot SA12 7AX (United Kingdom)

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{sub 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{sub 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{sub 3} catalysts, in pyridine, have the highest nitrogen-doping level, show a helical morphology and are less thermally stable compared with those synthesized by use of the para-CN and -Cl as catalyst. This suggests that fluorine heteroatoms enhance nitrogen-doping in N-CNTs and formation of helical-N-CNTs (H-N-CNTs). The para-CF{sub 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{sub 3} catalyst in acetonitrile gave N-CNTs as the only shaped carbon nanomaterials. - Graphical abstract: Graphical abstract showing the synthesis of N-CNTs using halogenated-ferrocenyl derivatives as catalyst with pyridine or acetonitrile as nitrogen and carbon sources via the chemical vapour deposition technique. - Highlights: • N-CNTs were synthesized from halogenated ferrocenyl catalysts. • Halogenated catalysts promote nitrogen-doping and pyridinic nitrogen in N-CNTs. • Halogenated catalysts facilitate iron filling of N-CNTs.

• OSTI ID: 22577803
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. 235; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ACETONITRILE
CARBON FIBERS
CARBON NANOTUBES
CARBON NITRIDES
CATALYSTS
CHEMICAL VAPOR DEPOSITION
CHLORINE
COMPARATIVE EVALUATIONS
CYANIDES
DOPED MATERIALS
FLUORINE
IRON
MIXTURES
NANOMATERIALS
NITROGEN
NUCLEAR MAGNETIC RESONANCE
PYRIDINE
X RADIATION
X-RAY DIFFRACTION
YIELDS