Some perspectives on nitrogen-doped carbon nanotube synthesis from acetonitrile and N,N′-dimethylformamide mixtures

• Published in: Materials chemistry and physics 2017-09, Vol.199, p.435-453
• Main Authors: Mombeshora, Edwin T., Jarvis, A.L.Leigh, Ndungu, Patrick G., Doyle, Bryan P., Carleschi, Emanuela, Nyamori, Vincent O.
• Format: Article
• Language: English
• Subjects: Acetonitrile; Carbon nanotubes; Chemical elements; Chemical synthesis; Chemical vapor deposition; Gravimetric analysis; Influence; N,N′-dimethyl formamide; Nanotubes; Nitrogen; Nitrogen atoms; Nitrogen sources; Nitrogen-doping; Studies; Transmission electron microscopy; X ray powder diffraction
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2017.07.044

This work reports on the influence of the ratio of sp3 (N,N′-dimethylformamide, DMF) to sp (acetonitrile) hybridised nitrogen within the carbon source used in the synthesis of nitrogen-doped carbon nanotubes (N-CNTs) by means of the floating catalyst chemical vapour deposition method. The physicochemical properties of the N-CNTs were investigated by means of scanning and transmission electron microscopies, textural characteristics, powder X-ray diffraction, X-ray photoelectron spectroscopy, thermal gravimetric analysis and elemental analysis. When the two nitrogen sources were compared before mixing, it was found that sp3 hybridised nitrogen in DMF was a more effective source for the incorporation of nitrogen atoms (5.87%) than sp hybridised nitrogen in acetonitrile (3.49%). The number of walls within the N-CNT synthesised from the sp3 nitrogen source was tailored by changing the synthesis temperature. Overall, a 1:3 sp3:sp ratio produced N-CNTs with the highest nitrogen content of 9.38% and a general abundance of pyrrolic nitrogen moieties within the samples. The best synthesis temperature in terms of nitrogen content and largest composition of N-CNTs with least residual iron was found to be 900 °C. Varying ratio of sp3:sp hybridised nitrogen is suitable for tailoring the physicochemical properties of N-CNTs towards preferred applications. [Display omitted] •Sp3:sp reagent ratios were varied in N-doped carbon nanotubes (N-CNTs) synthesises.•Varying sp3:sp nitrogen sources ratio tailored N-CNT physicochemical properties.•The sp3:sp ratio of 1:3 had highest N-doping content of 9.38%.•The major nitrogen moieties in the N-CNTs was pyrrolic.•Highest yield of N-CNTs was obtained at 900 °C.