TY - JOUR

T1 - Controlling pyridinic, pyrrolic, graphitic, and molecular nitrogen in multi-wall carbon nanotubes using precursors with different N/C ratios in aerosol assisted chemical vapor deposition

AU - Bulusheva, L. G.

AU - Okotrub, A. V.

AU - Fedoseeva, Yu V.

AU - Kurenya, A. G.

AU - Asanov, I. P.

AU - Vilkov, O. Y.

AU - Koós, A. A.

AU - Grobert, N.

PY - 2015

Y1 - 2015

N2 - Nitrogen-containing multi-wall carbon nanotubes (N-MWCNTs) were synthesized using aerosol assisted chemical vapor deposition (CVD) techniques in conjunction with benzylamine:ferrocene or acetonitrile:ferrocene mixtures. Different amounts of toluene were added to these mixtures in order to change the N/C ratio of the feedstock. X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy detected pyridinic, pyrrolic, graphitic, and molecular nitrogen forms in the N-MWCNT samples. Analysis of the spectral data indicated that whilst the nature of the nitrogen-containing precursor has little effect on the concentrations of the different forms of nitrogen in N-MWCNTs, the N/C ratio in the feedstock appeared to be the determining factor. When the N/C ratio was lower than ca. 0.01, all four forms existed in equal concentrations, for N/C ratios above 0.01, graphitic and molecular nitrogen were dominant. Furthermore, higher concentrations of pyridinic nitrogen in the outer shells and N2 molecules in the core of the as-produced N-MWCNTs suggest that the precursors were decomposed into individual atoms, which interacted with the catalyst surface to form CN and NH species or in fact diffused through the bulk of the catalyst particles. These findings are important for a better understanding of possible growth mechanisms for heteroatom-containing carbon nanotubes (CNTs) and therefore paving the way for controlling the spatial distribution of foreign elements in the CNTs using CVD processes.

AB - Nitrogen-containing multi-wall carbon nanotubes (N-MWCNTs) were synthesized using aerosol assisted chemical vapor deposition (CVD) techniques in conjunction with benzylamine:ferrocene or acetonitrile:ferrocene mixtures. Different amounts of toluene were added to these mixtures in order to change the N/C ratio of the feedstock. X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy detected pyridinic, pyrrolic, graphitic, and molecular nitrogen forms in the N-MWCNT samples. Analysis of the spectral data indicated that whilst the nature of the nitrogen-containing precursor has little effect on the concentrations of the different forms of nitrogen in N-MWCNTs, the N/C ratio in the feedstock appeared to be the determining factor. When the N/C ratio was lower than ca. 0.01, all four forms existed in equal concentrations, for N/C ratios above 0.01, graphitic and molecular nitrogen were dominant. Furthermore, higher concentrations of pyridinic nitrogen in the outer shells and N2 molecules in the core of the as-produced N-MWCNTs suggest that the precursors were decomposed into individual atoms, which interacted with the catalyst surface to form CN and NH species or in fact diffused through the bulk of the catalyst particles. These findings are important for a better understanding of possible growth mechanisms for heteroatom-containing carbon nanotubes (CNTs) and therefore paving the way for controlling the spatial distribution of foreign elements in the CNTs using CVD processes.

UR - http://www.scopus.com/inward/record.url?scp=84941890901&partnerID=8YFLogxK

U2 - 10.1039/c5cp01981h

DO - 10.1039/c5cp01981h

M3 - Article

AN - SCOPUS:84941890901

VL - 17

SP - 23741

EP - 23747

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

SN - 1463-9076

IS - 37

ER -