An experimental and theoretical examination of the effect of sulfur on the pyrolytically grown carbon nanotubes from sucrose-based solid state precursors

• Published in: Carbon (New York) 2011-02, Vol.49 (2), p.508-517
• Main Authors: Kucukayan, Gokce, Ovali, Rasim, Ilday, Serim, Baykal, Beril, Yurdakul, Hilmi, Turan, Servet, Gulseren, Oguz, Bengu, Erman
• Format: Article
• Language: English
• Subjects: adsorption; Atomic structure; Carbon; Carbon nanotubes; Catalysis; catalysts; Chemistry; Cross-disciplinary physics: materials science; rheology; Defects; Density; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; General and physical chemistry; Materials science; Mathematical models; nanoparticles; Physics; pyrolysis; solids; Specific materials; sucrose; Sulfur; sulfuric acid; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Yttrium
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2010.09.050

Sulfur prefers binding to defect sites on the side-walls of CNTs. [Display omitted] ► MWCNTs were synthesized by the pyrolysis of H 2SO 4 carbonized byproduct of sucrose. ► Sulfur prefers binding to existing non-hexagonal defects. ► Non-hexagonal defects can act as nucleation sites for Y-junctions. Multi-walled carbon nanotubes (MWCNTs) were synthesized through pyrolysis of the sulfuric acid-carbonized byproduct of sucrose. While the presence of sulfur in the reaction media has a key role in the formation and population density of MWCNTs, we have not observed the formation of Y-junctions or encountered other novel carbon nanotube formations. Results indicate the presence of sulfur in catalyst particles trapped inside nanotubes, but failed to find sulfur in the side-walls of the CNTs. In order to verify and explain these findings, we analyzed the behavior of sulfur and its possible effects on the side-wall structure of CNTs by using density functional theory-based calculations on various atomic models depicting sulfur inclusion in the side-walls. The results of the computational study were in line with the experimental results and also provided a new perspective by suggesting that the defects such as pentagons may act as nucleation sites for the Y-branches. The results indicated that sulfur prefers to adsorb on these defective regions, but it is not responsible for the formation of these structures or defects.