Nitrogen-Doped Carbon Nanotubes from Amine Flames

Abstract

A novel approach has been developed for synthesizing nitrogen-doped carbon nanotubes (N-CNTs) from flames using liquid amines as fuels, such as isopropylamine, n-propylamine and n-butylamine, which not only created a high reaction temperature but also provided a source of C and N. The microstructure and morphologies of the N-CNTs were characterized by scanning and transmission electron microscopy, laser Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. These N-CNTs were different from the conventional N-CNTs from a chemical vapor deposition process with primarily a 'pyridine-like' structure at N substitutions (one N atom only bonded to two C atoms). They were dominantly 'graphite-like' (one N atom substituted for C in graphite layers and bonded to three C atoms) with few C congruent N bonds due to the special formation conditions of high temperature and oxidative environment. It was found that: (1) amine fuel with a side chain structure was less suitable for preparation of orderly grown N-CNTs; (2) amine fuels with a higher N content generally introduced a larger quantity of N dopant; (3) the proportion of the 'graphite-like' N dopant decreased with increasing flame temperature, which provided a possibility for controllable N doping in N-CNTs from amine flames. The growth mechanism of the N-CNTs was also simulated and discussed.

One-dimensional nitrogen-containing carbon nanostructures

“…Pyrolysis of alkylamines was also frequently employed synthetic route to NCNTs, mainly MWNCNTs (Table 3) [101,[131][132][133][134][135][136][137][138][139][140][141][142][143][144][145][146]. A novel simple approach, quite different from classic CVD processes, has recently been developed for synthesizing NCNTs from flames using liquid alkylamines as fuels, which created a high reaction temperature and provided a C/N source [132].…”

“…A novel simple approach, quite different from classic CVD processes, has recently been developed for synthesizing NCNTs from flames using liquid alkylamines as fuels, which created a high reaction temperature and provided a C/N source [132]. When NCNTs were synthesized from three different aliphatic diamine compounds, increasing the N/C ratio in the precursor solution resulted in higher N contents in the synthesized NCNTs [144,145].…”

Synthesis and electrochemical applications of nitrogen-doped carbon nanomaterials

“…The carboxyl groups may then be acylated with thionyl chloride to make a basis for the various amine compounds [63] or to attach to the various proteins and DNA [64,65]. The other commonly used chemical reactions to attach the organic groups include the cyclo additions (e.g., Bingel, Diels Alder), electrophilic and nucleophilic additions, ozonolysis, halogenations, or radical reactions (oxidative and reductive) [66][67][68]. The CNTs can also be synthesized by the arc evaporation of graphite [47,49,69] or by exploiting the pyrolysis of the hydrocarbons in the presence of the metal particles, particularly using the CVD method [42,70,71] or more attempting method of chemical modification [72,73].…”

“…In a similar way, lysine was covalently attached onto the MWCNT side walls, resulting in the nanomaterials that show a high dispersibility in deionized water (10 mg/ml) [66]. The other materials used, including the alkylamines [98], octaamino-substituted erbium bisphthalocyanine [99], and the metal-based [79] ferrocene and melamine [68,82,100], n-propylamine and n-butylamine [67], poly-amido amine [63], ferrocene/acetonitrile [84], cationic polyelectrolyte poly(diallyldimethylammonium) chloride [64], dendrimer [65,101], increases the CNT's activity/properties on doping. Hydrazine hydrate and diethyltriamine were doped to increase the water dispersion ability of the CNT [102].…”

“…The fast reaction rate on these N-CNT arrays and electron transfer rate from the substrate to the N-CNTs manifest much higher cathodic and anodic peak current densities than those of the Pt electrode, indicating a higher electrochemical activity for these tubes [14]. The "graphite-like" N dopant in the as-grown N-CNTs enhances their surface chemical activity and conductivity and presents the desirable performance for the electrochemical supercapacitors [67]. The electrochemical intercalation of the N-CNTs with lithium makes them a promising anodic source in the Li ion batteries [54].…”